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BIOL 314 Master Deck

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Which of the following is not an example of a connective tissue? (a) bone (b) the layer of photoreceptors in the eye (c) the jellylike interior of an eye (d) cartilage

Which of the following is not found in ALL bacterial cells? a) cell membrane b) nucleus c) ribosomes d) DNA

Gene amplification of a tumor suppressor gene PTEN is more dangerous than gene amplification of a proto- oncogene. (a) True (b) False

FALSE

Which of the following organelles has both an outer and an inner membrane? a) endoplasmic reticulum b) mitochondrion c) lysosome d) peroxisome e) ribosome

Which of the following proteins is NOT associated with microfilaments? a) Actin b) Tau c) Arp2/3 d) Myosin e) Gelsolin

Is the following statement true or false? Explain. The phenotype of an organism reflects all of the alleles carried by that individual.

FALSE

I am a small organelle that is partially made up of RNA. What am I? a) An endosome b) A lysosome c) A ribosome d) The rough endoplasmic reticulum e) A plastid

I am thinking of a polymer -- any polymer. Which polymer am I thinking of? a) cAMP b) adenosine c) keratin d) phosphatidylserine e) retinoic acid

In the absence of recombination, how many genetically different types of gamete can an organism with five homologous chromosome pairs produce? (a) 5 (b) 10 (c) 32 (d) 64

The __________ __________ is made up of two concentric membranes and is continuous with the membrane of the endoplasmic reticulum. a) plasma membrane b) Golgi network c) mitochondrial membrane d) nuclear envelope e) cell wall

The artificial introduction of three key ______________ into an adult cell can convert the adult cell into a cell with the properties of ES cells. (a) chromosomes (b) viruses (c) hormones (d) transcription factors

The cell cycle consists of an alternation between __________________, which appears as a period of dramatic activity under the microscope a. G1 b. S c. G2 d. M e. interphase

Cell plasma membranes are composed of approximately equal parts (depending on the cell type)... a) lipids and protein b) peas and carrots c) wishes and broken promises d) stupid professors and annoying bureaucracy e) pencils and strange talking dust particles named Saucy Maria

Cells in the G0 state ________________. (a) do not divide. (b) cannot re-enter the cell cycle. (c) have entered this arrest state from either G1 or G2. (d) have duplicated their DNA.

Consider a protein that contains an ER signal sequence at its N-terminus and a nuclear localization sequence in its middle. What would be the most likely fate of this protein? a) The protein would be translocated into the ER. b) The protein would be transported into the nucleus. c) The protein would remain in the cytoplasm. d) The protein would become part of the nuclear pore complex. e) The protein would be degraded.

Cytokinesis in animal cells ________________. (a) requires ATP. (b) leaves a small circular "scar" of actin filaments on the inner surface of the plasma membrane. (c) is often followed by phosphorylation of integrins in the plasma membrane. (d) is assisted by motor proteins that pull on microtubules attached to the cell cortex

DNA damage can arrest the cell cycle in G1 by stabilizing _____. (a) p53 (b) p21 (c) APC (d) Rb

Which of the following would not explain the results with the mutant? (a) inability to initiate DNA replication (b) inability to begin M phase (c) inability to activate proteins needed to enter S phase (d) inappropriate production of a signal that causes the cells to remain in G1

(b) inability to begin M phase

What would be the most obvious outcome of repeated cell cycles consisting of S phase and M phase only? (a) Cells would not be able to replicate their DNA. (b) The mitotic spindle could not assemble. (c) Cells would get larger and larger. (d) The cells produced would get smaller and smaller.

(d) The cells produced would get smaller and smaller.

In which phase of the cell cycle do cells check to determine whether the DNA is fully and correctly replicated? (a) at the transition between G1 and S (b) when cells enter G0 (c) during M (d) at the end of G2

(d) at the end of G2

The four phases of the cell cycle, in order, are G1, __________________, __________________, and __________________. A cell contains the most DNA after __________________ phase of the cell cycle. A cell is smallest in size after __________________ phase of the cell cycle. Growth occurs in __________________, __________________, and __________________ phases of the cell cycle. A cell does not enter mitosis until it has completed __________________ synthesis. DNA M protein G1 nucleotide S G2 organelle

, S, G2 M S M G1, S, G2 DNA

Do endosomes have membranes? a) Yes, of course. They are by definition basically blobs of membrane. b) No. c) Yes, but only under certain conditions d) Endosomes are not organelles e) Only in prokaryotic cells

The first step in tumor development is usually... a) accumulation of mutations that lead to cell proliferation b) angiogenesis c) metastasis d) progression e) triggered by release of VEGF

The principal microtubule-organizing center in animal cells is the ____________. (a) centrosome. (b) centromere. (c) kinetochore. (d) cell cortex

'Dynasore' is a drug that disrupts dynamin. Dynamin does not work in cells treated with dynasore. Now lets do the experiment described in question #31, but in cells treated with dynasore: If you treat a cell with dynosore, and then with FM1-43, what will most likely happen? a) The plasma membrane would fluoresce, and then nothing else would fluoresce. b) The plasma membrane would fluoresce, then vesicles traveling retrograde, then the golgi. c) The ER would fluoresce first, then the golgi, then vesicles. d) Nothing would fluoresce, because FM1-43 cannot cross lipid bilayers.

19) ALL cells... a) are enclosed by a plasma membrane and contain DNA. b) contain a nucleus. c) contain mitochondria. d) are believed to have evolved from an ancestral cell that existed more than 13.5 billion years ago. e) are protozoans.

Which of the following is probably the WORST idea for a cancer treatment? a) An inhibitor of caspases b) An inhibitor of VEGF c) A growth factor inhibitor d) A cyclin inhibitor e) An inhibitor of DNA replication enzymes

A bacterial cell membrane consists of 25% phospholipids and 75% proteins. Proteins can either be integral membrane proteins (embedded in the membrane) or peripheral membrane proteins (interacting with the lipids' polar heads). The largest group of integral membrane proteins is responsible for what? a) Transport of charged solutes b) Cell defense c) Motility d) Membrane synthesis

A biopsy is taken from a person's skin epithelial tissue and was examined under a microscope. A skin expert looking at the tissue sample was surprised to see that a large number of the cells had the appearance of much larger nuclei than normal skin tissue. Which of the following could explain this occurrence? a) The cells are undergoing rapid proliferation and the abnormal amount of these proliferating cells can be a sign of cancer. b) Cell growth is quite slow in this particular tissue sample. c) The cells in this sample are preparing to undergo apoptosis. d) There is a problem with the intermediate filaments of the cells causing the nuclei to expand. e) The cells are undergoing abundant proliferation, indicating that this individual's skin is especially healthy.

A cell can crawl through a tissue because of the transmembrane ______________ proteins that can bind to fibronectin outside of the cell. (a) integrin (b) collagen (c) gap junction (d) claudin

A double strand DNA breakage will induce PUMA expression, which will in turn promote apoptosis by inhibiting _____. (a) Bcl2 (b) Bad (c) p21 (d) E2F

A friend declares that chromosomes are held at the metaphase plate by microtubules that push on each chromosome from opposite sides. Which of the following observations does not support your belief that the microtubules are pulling on the chromosomes? (a) the jiggling movement of chromosomes at the metaphase plate (b) the way in which chromosomes behave when the attachment between sister chromatids is severed (c) the way in which chromosomes behave when the attachment to one kinetochore is severed (d) the shape of chromosomes as they move toward the spindle poles at anaphase

A gene called SRY on the human Y chromosome produces a DNA-binding protein required for the development of testes. Testes are organs that produce hormones that cause differentiation of male features. Without SRY, ovaries form, and the fetus becomes female. One of the most important male hormones is a steroid hormone called 'testosterone'. Testosterone is synthesized from cholesterol, mainly within Leydig cells in the testes. Which organelle is the primary location for testosterone synthesis? a) Smooth endoplasmic reticulum b) Rough endoplasmic reticulum c) Ribosomes d) Mitochondria e) Nucleus

A metastasis is _________. (a) a secondary tumor in a different part of the body that arises from a cell from the primary tumor. (b) a cell that is dividing in defiance of normal constraints. (c) a part of the primary tumor that has invaded the surrounding tissue. (d) the portion of the cancerous tumor that displays genetic instability

A particular hormone is discovered to induce its effects by binding to surface proteins of receptor cells rather than passing through the membrane and activating intracellular receptors. This hormone is most likely which of the following types? a) peptide hormone b) steroid hormone c) hydrophilic hormone d) The answer cannot be determined with the given information.

A protein's functions are inhibited by a kinase. They activated by a phosphatase. Respectively, what are the actions of the kinase and phosphatase? a) phosphorylation, dephosphorylation b) dephosphorylation, phosphorylation c) Lower the system's overall kinetic energy, Increase the system's overall potential energy d) Increase the system's overall kinetic energy, Decrease the system's overall potential energy

A tubulin GAP (GTPase Activating Protein), which would accelerate hydrolysis of GTP associated with tubulin, would... a) increase microtubule dynamic instability b) promote the growth of cilia c) trigger the formation of 'actin tails' on the ends of bacteria d) cause the breakdown of the nuclear lamina e) assist in the formation of a 'GTP cap'

ALL cells... a) are enclosed by a plasma membrane and contain DNA. b) contain a nucleus. c) contain mitochondria. d) are believed to have evolved from an ancestral cell that existed more than 13.5 billion years ago. e) are protozoans.

According to the Skin Cancer Foundation website, skin cancer is the most common form of cancer in the United States. More than 3.5 million skin cancers in over two million people are diagnosed annually. Each year there are more new cases of skin cancer than the combined incidence of cancers of the breast, prostate, lung and colon. One in five Americans will develop skin cancer in the course of a lifetime. Over the past 31 years, more people have had skin cancer than all other cancers combined. This is perhaps not surprising, given that skin contains a high proportion of the body's epithelial cells and is exposed to many types of mutagens. Based on this information and the information presented in class, which of the following is TRUE? a) Skin cancers are carcinomas. b) In the U.S., lymphomas and leukemias are more common than skin cancers. c) Skin cancer cells are undergoing apoptosis. d) Hyperplasia is suppressed in skin cancer. e) Skin cancer does not involve metastasis.

Actin filaments are found in all of the following EXCEPT the a) flagella of bacteria b) sarcomeres of skeletal muscle cells c) stress fibers of fibroblasts d) microvilli of the intestinal brush border e) contractile rings of dividing animal cells

Actin filaments are found in all of the following EXCEPT the... a) flagella of bacteria b) sarcomeres of skeletal muscle cells c) stress fibers of fibroblasts d) microvilli of the intestinal brush border e) contractile rings of dividing animal cells

Adherens junctions ______________________. (a) can be used to bend epithelial sheets into tubes. (b) are most often found at the basal surface of cells. (c) are found only in adult tissues. (d) involve fibronectin and integrin interactions

All life as we know it is composed of one or more... a) cells b) organs c) pieces of aluminum d) ancient sailing ships e) magical levitating elves that say "whoop whoop whoop"

All of the following are known to be part of a signal transduction cascade EXCEPT (A) phosphorylation of fibronectin (B) dissociation of the components of a heterotrimeric G-protein (C) enzymatic breakdown of phosphatidyl inositol bisphosphate (PIP2 ) (D) elevation of intracellular [Ca2+] (E) activation of cGMP phosphodiesterase

All of the following statements about the type-B cyclin proteins are correct EXCEPT: a) Their presence is required for exit from mitosis b) They are present in cells during the G2 phase c) They are degrade via the ubiquitin pathway d) They activate the Cdc2 kinase e) They are newly synthesized during every cell cycle

Anaphase-promoting complex... a) ubiquitylates securin and mitotic cyclin, thereby triggering their destruction and progression through mitosis. b) associates with and activates CDK proteins. c) is an enzyme that degrades CDK proteins. d) associates with caspases and suppresses apoptosis after DNA damage. e) is inhibited by Avastin.

Aside from water, which of the following is generally most abundant in cells? a) Protein b) Lipids c) Polysaccharides d) RNA e) DNA

At the start of mitosis (exploring mode), M-cdks phosphorylate Microtubule binding proteins and thus increases ________ of MT. Then, MTs from each pole interact and become stabilized: forming interpolar microtubule. (a) the dynamic instability (b) interaction with F-Actin (c) interaction with Centromere (d) interaction with Telomere

Both budding yeast and the bacteria E. coli are unicellular life. Which of the following statements explains why budding yeast can undergo sexual reproduction while E. coli cannot. (a) Unlike E. coli, budding yeast can alternate between a diploid state and a haploid state. (b) Unlike E. coli, budding yeast cannot multiply by undergoing cell division. (c) Unlike E. coli, haploid budding yeast cells can undergo meiosis to produce the gametes necessary for sexual reproduction. (d) E. coli DNA is unable to undergo homologous recombination, making it incapable of producing gametes.

By definition, prokaryotic cells do not possess __________. (a) a nucleus. (b) replication machinery. (c) ribosomes. (d) membrane bilayers.

CDK is... a) a type of protein that phosphorylates other proteins when associated with regulatory proteins called cyclins. b) a type of protein that promotes progression through the cell cycle by removing phosphate groups from other proteins. c) an inhibitor of cyclin-dependent kinases. d) a signaling molecule produced by cyclins. e) activated by cAMP to induce cell proliferation.

CDK stands for _________. (a) Cyclin Dependent Kinase (b) Cell Division Kinase (c) Cyclic Diester Kinase (d) Cytoplasmic Dynein Kinase

Carbons from sugars and fatty acids enter the citric acid cycle as... a) Acetyl CoA b) Pyruvate c) Carbon dioxide d) NADH e) Glucose 6-phosphate

Fertilization of an egg cell by a sperm cell causes the egg cell to begin proliferating and differentiating. The diagram to the right shows some of the signaling pathways involved in fertilization. According to the diagram, a PIP2 inhibitor would do which of the following things to the egg cell? a) suppress CDK activity b) activate P53 c) increase DAG d) increase the rate of cell proliferation e) decrease caspase activity

Heat is a byproduct of metabolism. Brown fat is a type of fat that is abundant in newborns and hibernating animals. Brown fat is specialized for generating heat. Brown fat has a higher density of mitochondria than normal 'white' fat, and the iron in the mitochondria are what make brown fat brown. Brown fat mitochondria contain a higher density of a protein called 'thermogenin', compared to other cell types. Given that brown fat is specialized for generating heat instead of energy, which of the following is TRUE? a) Thermogenin is also known as uncoupling protein 1 (UCP1), and it allows protons to flow across the mitochondrial inner membrane instead of through ATPase. b) Brown fat preferentially performs anaerobic metabolism rather than aerobic metabolism. c) Cyanide increases cellular heat production. d) Thermogenin is a protein kinase that regulates the speed of glycolysis. e) White fat does not contain mitochondria.

I am an ever-changing network of tubules spreading throughout the cell cytoplasm. I contain nucleic acids and have a double membrane. What am I? a) A mitochondrion b) A nucleus c) The endoplasmic reticulum d) The golgi apparatus e) An endosome

If a cell is injured, it can lyse and die in a relatively uncontrolled manner. This process is... a) called 'necrotic cell death'. b) called 'apoptosis'. c) triggered by caspase activation. d) dependent upon cyclin dependent kinases. e) both b and c.

If a cell is injured, it can lyse and die in a relatively uncontrolled manner. This process... a) is called 'nectrotic cell death' b) is called 'apoptosis'. c) depends on caspase activation. d) depends upon cyclin dependent kinase activity. e) requires phosphorylation of Rb protein

If you crossed the round-seeded plants obtained in the F1 generation with a true-breeding strain of round-seeded plants, how many wrinkle-seeded plants would you expect to obtain in the next generation? (See Figure Q19-38.) (a) none (b) 25% (c) 75% (d) all

Immediately after fertilization, chicken eggs... a) are totipotent stem cells b) are fully differentiated c) are unresponsive to teratogens d) are prokaryotic e) do not yet contain a complete chicken genome

In Eukaryotes, the mitochondria membrane possesses a series of complexes that play vital roles in oxidative phosphorylation. In bacteria, where would one expect to find structures homologous to the complexes found in the mitochondria of a eukaryote? a) Embedded in the plasma membrane. b) Embedded in the membrane of a bacterial mitochondria. c) Embedded in the Glycocalyx d) In the nucleoid.

Increasing evidence suggests that many neurodegenerative diseases (like Alzheimer's, Parkinson's, and amyotrophic lateral sclerosis (ALS) are linked to defects in intracellular transport. In many of these diseases, cells fail to move vesicles and organelles properly. This leads to problems in neurons, which require lots of intracellular transport. 'Sprawling' (swl), 'cramping' (cra), and 'legs at odd angles' (loa) are mouse mutants that show symptoms similar to patients with ALS. Swl, cra, and loa mutations disrupt which type of protein? a) Dynein heavy chain b) ARP2 c) Keratin d) Actin e) Nexin

Induced pluripotent stem (iPS) cells ______________________. (a) are created by the expression of a set of key genes in cells derived from adult tissues so that these cells can differentiate into a variety of cell types. (b) require a supply of donor egg cells, such as embryonic stem cells. (c) can differentiate into a greater variety of adult tissues than embryonic stem cells. (d) are created by nuclear transplantation.

Inflammation and cell proliferation involve activation of cyclooxygenase (COX) enzymes. COX enzymes that catalyze the formation of prostaglandins from fatty acids. Prostaglandins are signaling molecules. There are three COX enzymes: COX-1, COX-2, and COX-3. COX-2 activity is basically undetectable in normal tissues, but upregulated during inflammation and in many tumor cells. Nonsterioidal anti-inflammatory drugs (NSAIDs), like aspirin and ibuprofen, inhibit COX enzymes. Recently, a long-term study of aspirin's effects on cardiovascular health revealed that people taking low doses of aspirin for years also had lower incidence of colon cancer. Based on this, which of the following is likely TRUE? a) Prostaglandins promote angiogenesis. b) NSAIDs promote stem cell proliferation. c) COX-2 is a type of CDK. d) Tumor cells do not contain fatty acids. e) Aspirin suppresses apoptosis.

Microtubule-dependent motor proteins and microtubule polymerization and depolymerization are mainly responsible for the organized movements of chromosomes during mitosis. (a) True (b) False

Mitogens are _____. (a) extracellular signals that stimulate cell division. (b) transcription factors important for cyclin production. (c) kinases that cause cells to grow in size. (d) produced by mitotic cells to keep nearby neighboring cells from dividing

Movement of ions across the membrane from higher to lower concentrations through a channel protein is an example of A Facilitated diffusion B Simple diffusion C Active transport D Osmosis

Movement of ions across the membrane from higher to lower concentrations through a channel protein is an example of a) Facilitated diffusion b) Simple diffusion c) Active transport d) Osmosis

Which of the following is used to treat flunitrazepam overdoses? a) Romazicon, a benzodiazepine receptor antagonist b) BNZ2 agonists such as Clorazepate c) GABA d) Carisoprodol, a muscle relaxant e) All of the above would make the effects of flunitrazepam worse.

Mutations in the gene that encodes human axonemal nexin are likely to cause... a) male infertility due to immobile sperm b) flaccid paralysis due to lack of muscle contraction c) open sores due to lack of epithelial cell adhesion d) severe brain development problems due to altered axon outgrowth e) numbness due to an inability of nerve fibers to transmit electrical signals

Nocadazol binds tubulin and inhibits structural microtubule assembly at the positive end. Which of the following would most likely be seen in a patient after a nocadazol injection? a) tubule destabilization due to incomplete polymerization b) incomplete nexin links c) completely inhibited dynein ATPase activity d) increased synthesis of rigid cilia

One way in which mitogens stimulate cell proliferation is activating G1-Cdk which in turn inhibits ______. (a) Rb (b) E2F (c) APC (d) Myc

Ovaries produce a lot of estrogen. Male transsexuals who use estrogen to give themselves a female appearance have increased risk of breast cancer, but not prostate or skin cancer. What is the most likely explanation for this? a) Estrogen is a mitogen. b) Estrogen is a tumor suppressor. c) Estrogen facilitates DNA repair. d) Estrogen is an oncogene. e) Estrogen is an anti-angiogenesis factor.

Plasmodesmata ______________________. (a) permit small molecules to pass from one cell to another. (b) are found only in animal cells. (c) are closed by the neurotransmitter dopamine. (d) provide tensile strength

Programmed cell death occurs ________________. (a) by means of an intracellular suicide program. (b) rarely and selectively only during animal development. (c) only in unhealthy or abnormal cells. (d) only during embryonic development.

Proteins that are fully translated in the cytosol and lack a sorting signal will end up in ____. (a) the cytosol. (b) the mitochondria. (c) the interior of the nucleus. (d) the nuclear membrane.

Pumps are transporters that are able to harness energy provided by other components in the cells to drive the movement of solutes across membranes, against their concentration gradient. This type of transport is called _____________. (a) active transport (b) free diffusion (c) facilitated diffusion (d) passive transport

Pumps are transporters that are able to harness energy provided by other components in the cells to drive the movement of solutes across membranes, against their concentration gradient. This type of transport is called _____________. a) active transport b) free diffusion c) facilitated diffusion d) passive transport e) public transport

SNARE proteins are found in the membranes of all of the following compartments EXCEPT (A) Mitochondria (B) Golgi complex (C) Early endosome (D) Endoplasmic reticulum (E) Synaptic plasma membrane

Saturated fats are usually solid at room temperature. Why? a) The relatively straight fatty acid tails pack together better than in unsaturated fats. b) The fatty acid tails in saturated fats prevent tight packing of lipid tails. c) Saturated fatty acids have longer fatty acid tails. d) Saturated fatty acids have more carbon-carbon double bonds, reducing lipid mobility. e) Cis double bonds in saturated fatty acids interact to reduce membrane fluidity.

Sea urchins, in case you were wondering, are spiky creatures that live on the sea bottom. To the right there is a picture of a sea urchin. Male sea urchins, like male humans, have testes and use testosterone as a hormone. Testosterone is an androgen. The wikipedia entry for 'Androgen' says: "Androgen, also called androgenic hormone or testoid, is the generic term for any natural or synthetic compound, usually a steroid hormone, that stimulates or controls the development and maintenance of male characteristics in vertebrates by binding to androgen receptors." Which of the following is TRUE? a) Androgen receptor activation regulates transcription factor activity. b) Androgen receptors suppress CDK activity. c) Testosterone is a phospholipid. d) A single molecule of protein kinase A weighs less than a single molecule of cAMP. e) Sea urchins are prokaryotes.

Selective destruction of which location will greatly reduce the concentration of growth hormone receptors? a) the plasma membrane b) the cytosol c) the nucleus d) the nucleolus

Some vesicles move from the golgi to the plasma membrane. What could explain this? a) The vesicles are attached to kinesins. b) The vesicles are attached to dyneins. c) The vesicles are really large and it is windy outside. d) The vesicles inhibit myosin. e) The vesicles contain collagen

Stem cells... a) are less differentiated than neurons b) are found only in embryos c) cannot be grown in the lab d) express all genes in the genome at approximately equal levels, at pretty much at the same time e) form gradients in developing embryos

Testosterone has long been thought to be associated with male prostate cancer. The study "Testosterone Therapy in Men with Untreated Prostate Cancer" was published in The Journal of Urology April 2011, suggests that this is not true. Given this information, which of the following is therefore likely to be TRUE? a) Testosterone does not increase CDK activity in prostate cells b) Testosterone reduces apoptosis in prostate cells c) Testosterone allows cells to progress more rapidly through the cell cycle d) Testosterone is produced primarily in the prostate gland. e) Testosterone suppresses Rb activity.

The 23 year old woman was addicted to caffeine. Caffeine is an inhibitor of phosphodiesterase. After drinking another cup of coffee, her cells would have increased level of: a) cAMP b) Phospholipase c) Mitochondria d) ADP e) Caffeine Kinase

The activity of a Cdk can be blocked by the binding of____, a Cdk inhibitor. (a) p27 (b) p53 (c) APC (d) E2F

The concentration of sodium and calcium is much higher outside of cells, compared to inside. Which of the following types of transporters could move calcium from the inside of a cell to the outside? a) A sodium/calcium antiporter b) A calcium channel c) A sodium channel d) A sodium/calcium symporter that moves sodium into the cell. e) A sodium/potassium ATPase

The cytoskeletal framework inside a flagellum is called... a) An axoneme b) A sarcomere c) A basal body d) A dynein arm e) A filopodium

The survival, proliferation, and size of each cell in an animal are controlled by extracellular signal molecules secreted by neighboring and distant cells. One of these signal molecules bind to ____, a cell-surface receptor and trigger various intracellular signaling pathways. (a) PDGFR (b) MAPK (c) PKA (d) PKC

Transporters, in contrast to channels, work by ________________. a) specific binding to solutes b) a gating mechanism c) filtering solutes by charge d) filtering solutes by size e) asking their friends to do everything for them, complaining that their lives are too complicated and busy right now but really the problem is that they have no organization skills and are unwilling to accept responsibility for their own life.

Type I diabetes is caused by loss of pancreatic beta cells that synthesize and secrete insulin. Usually this cell loss occurs because the patient's immune system attacks and kills the insulin-producing pancreatic beta cells, for reasons that are not yet clear. In 2007, 15 early-stage diabetics in Brazil (the procedure was not approved in the U.S.) were given drugs to increase blood stem cell production. These cells were then harvested and saved while the patients' bone marrow was then killed with chemotherapy. The harvested stem cells were then re-injected, and gave rise to a new immune system that did not attack the remaining pancreatic beta cells. 14 of the 15 patients did not then need insulin injections for several years. Based on this information, which of the following is most likely TRUE? a) The harvested stem cells were pluripotent b) The harvested stem cells differentiated into pancreatic beta cells c) Insulin suppresses cell differentiation d) The patients can now be considered clones e) Pancreatic beta cells are stem cells

What are the main structures providing tensile strength in animal epidernis ? a. collagen fibers b. intermedaite filaments c. elastin d. microtubles

What is BRCA1? a) A DNA repair protein b) A type of retinoblastoma c) A breast cancer drug d) A molecule synthesized by tumor suppressor genes e) A type of G protein

What is the role of the nuclear localization sequence in a nuclear protein? (a) It is bound by cytoplasmic proteins that direct the nuclear protein to the nuclear pore. (b) It is a hydrophobic sequence that enables the protein to enter the nuclear membranes. (c) It aids in protein unfolding so that the protein can thread through nuclear pores. (d) It prevents the protein from diffusing out of the nucleus through nuclear pores.

What kind of molecule is metabolized in glycolysis? a) Sugars (glucose, for example) b) Amino acids (proteins) c) Large feet are really sweet d) My uncle was a boomerang e) Ich kann nicht englisch

When a terminally differentiated cell in an adult body dies, it can typically be replaced in the body by a stock of ________. (a) proliferating precursor cells. (b) cells more apically located than the terminally differentiated cells. (c) Wnt proteins. (d) induced pluripotent cells.

Which of the following accounts for the extent of proliferation observed in the retrovirus-infected cells NOT treated with growth factors? a) The v-erbB product has a function similar to that of activated EGF receptor b) EGF binds to both the EGF receptor and the v-erbB product c) The v-erbB product activates both the LCGF and the EGF receptors d) The v-erbB product antagonizes the action of the EGF receptor e) The v-erbB product induces secretion of EGF and LCGF

Which of the following do viruses NOT generally have? a) Ribosomes b) Proteins c) Nucleic acids d) Viruses have all of the above e) Viruses have none of the above, because they are not living things

Which of the following does not occur during M phase in animal cells? (a) growth of the cell (b) condensation of chromosomes (c) breakdown of nuclear envelope (d) attachment of chromosomes to microtubules

Which of the following genetic changes cannot convert a proto-oncogene into an oncogene? (a) A mutation that introduces a stop codon immediately after the codon for the initiator methionine. (b) A mutation within the coding sequence that makes the protein hyperactive. (c) An amplification of the number of copies of the proto-oncogene, causing overproduction of the normal protein. (d) A mutation in the promoter of the proto-oncogene, causing the normal protein to be transcribed and translated at an abnormally high level.

Which of the following is CORRECT? a) Connexins are gap junction proteins b) Ions and small molecules like glucose cannot pass through gap junctions c) Collagen and microtubules are important components of plant cell walls d) Desmosomes are transmembrane proteins involved in cell-cell junctions e) Keratin contributes to the strength of extracellular matrix

Which of the following is TRUE? a) Cell proliferation is regulated by protein kinases that consist of a catalytic (enzymatic) subunit called 'cyclin-dependent kinase', and a regulatory subunit, called 'cyclin'. b) Cyclins trigger degradation of APC by ubiquitinating it. c) Myostatin is a CDK protein that causes overproliferation of muscle cells when mutated. d) Cyclin is a transmembrane protein. e) Kinesins often contain signal sequences that bind to mitochondrial import proteins

Which of the following is TRUE? a) Akt is a kinase b) Akt is a phosphatase c) Viagra inhibits PI-3 kinase signaling d) The NO receptor translocates to the nucleus after binding NO, like other steroid recptors. e) PI-3 kinase inhibitors would increase erections

Which of the following is most likely to be involved with initiation and/or progression of cancer? a) Loss of G-protein GTPase activity downstream of a growth factor receptor b) Activation of P53 c) Activity of Rb protein, which represses expression of proteins required for cell cycle progression d) Immunotherapy e) Activation of proteases capable of breaking down the basal lamina

Which of the following organisms is likely to have the highest percentage of unsaturated fatty phospholipids in its membranes? a) Antarctic fish b) Desert snake c) Human being d) Polar bear e) Thermophilic bacterium that lives in hot springs at 100°C

Which of the following precede the re-formation of the nuclear envelope during M phase in animal cells? (a) assembly of the contractile ring (b) decondensation of chromosomes (c) reassembly of the nuclear lamina (d) transcription of nuclear genes

Which of the following reasons was essential for Mendel's law of independent assortment? (a) All the traits that Mendel examined involved genes that did not display linkage. (b) Several of the phenotypes that Mendel examined involved color. (c) Mendel observed chromosomal segregation in pea-plant cells. (d) Mendel carried out his experiments on plants and not on fungi.

Which of the following statements about collagen is false? (a) Collagen synthase organizes the mature collagen molecules into ordered collagen fibrils. (b) Collagen is synthesized as procollagen and secreted to the outside of the cell in a secretory vesicle. (c) The terminal procollagen domains are cleaved by a protease in the extracellular space. (d) Cells can break down a collagen matrix using matrix proteases.

Which of the following statements about integrins is false? (a) Integrins use adaptor proteins to interact with the microtubule cytoskeleton. (b) Integrins can switch to an activated state by binding to an extracellular matrix molecule. (c) Integrins can switch to an activated state by binding to an intracellular protein. (d) An activated integrin molecule takes on an extended conformation

Which of the following statements about kinetochores is true? (a) Kinetochores assemble onto chromosomes during late prophase. (b) Kinetochores contain DNA-binding proteins that recognize sequences at the telomere of the chromosome. (c) Kinetochore proteins bind to the tubulin molecules at the minus end of microtubules. (d) Kinetochores assemble on chromosomes that lack centromeres.

Which of the following statements about meiosis is true? (a) During meiosis, the paternal chromosomes pair with the maternal chromosomes before lining up at the metaphase plate. (b) Unicellular organisms that have a haploid state undergo meiosis instead of mitosis during cell division. (c) Meiosis produces four genetically identical cells. (d) In general, meiosis is faster than mitosis.

Which of the following statements about molecular switches is false? (a) Phosphatases remove the phosphate from GTP on GTP-binding proteins, turning them off. (b) Protein kinases transfer the terminal phosphate from ATP onto a protein. (c) Serine/threonine kinases are the most common types of protein kinase. (d) A GTP-binding protein exchanges its bound GDP for GTP to become activated.

Which of the following statements about plant cell walls is true? (a) The microtubule cytoskeleton directs the orientation in which cellulose is deposited in the cell wall. (b) The molecular components of the cell wall are the same in all plant tissues. (c) Because plant cell walls are rigid, they are not deposited until the cell has stopped growing. (d) The cellulose found in cell walls is produced as a precursor molecule in the cell and delivered to the extracellular space by exocytosis.

Which of the following statements about the benefits of sexual reproduction is false? (a) Sexual reproduction permits enhanced survival because the gametes that carry alleles enhancing survival in harsh environments are used preferentially during fertilization. (b) Unicellular organisms that can undergo sexual reproduction have an increased ability to adapt to harsh environments. (c) Sexual reproduction reshuffles genes, which is thought to help species survive in novel or varying environments. (d) Sexual reproduction can speed the elimination of deleterious alleles.

Which of the following statements about the endoplasmic reticulum ER) is false? a) The ER is NOT a major site for new membrane synthesis in the cell. b) Proteins to be delivered to the ER lumen are synthesized on rough ER. c) Steroid hormones are synthesized on the smooth ER. d) The ER membrane is contiguous with the outer nuclear membrane.

Which of the following statements about the experiment diagrammed in Figure Q19-38 is true? (a) If you crossed all the round-seeded pea plants from the F2 generation with true-breeding wrinkle-seeded pea plants, you would get more round-seeded pea plants in the next generation than if you crossed all the round-seeded pea plants from the F1 generation with true-breeding wrinkle-seeded pea plants. (b) The reason you do not see wrinkle-seeded pea plants in the F1 generation is because the round-seeded pea plants used to create the F1 generation were not true-breeding strains. (c) The gene for round-seeded pea plants is on a different chromosome from the gene for wrinkle-seeded pea plants, which is why you get 25% wrinkle-seeded pea plants in the F2 generation. (d) If you crossed the round-seeded pea plants from the F2 generation with the wrinkle-seeded pea plants from the F2 generation, you should get 100% round-seeded pea plants.

Which of the following statements is true? (a) Another name for the fertilized egg cell is the zygote. (b) Diploid organisms reproduce only sexually. (c) All sexually reproducing organisms must have two copies of every chromosome. (d) Gametes have only one chromosome

Which of the following things is TRUE about malignant tumors? a) Malignant tumor cells tend to contain mutations that activate oncogenes. b) Malignant tumor cells tend to have mutations that increase the activity of tumor suppressor proteins. c) Malignant tumors secrete factors that suppress angiogenesis. d) Malignant tumors tend to overexpress cadherins. e) Malignant tumors are all formed from epithelial cells.

Which of the following types of mutations is most likely to cause a genetically-linked cancer (e.g. a cancer found more often in related individuals)? a) Mutations in a tumor suppressor gene. b) Mutations that cause an increase in Rb protein. c) Mutations that increase VEGF signaling. d) Mutations that impair MAP kinase signaling pathways. e) Mutations that impair diacylglycerol production.

Which of the following would NOT change within a sarcomere during skeletal muscle contraction? a) The length of the myosin (thick) filaments b) The overlap between the myosin (thick) and actin (thin) filaments c) The position of the troponin-tropomysosin complexes on the actin (thin) filaments d) The positions at which the globular heads of the myosin (thick) filaments bind to the actin (thin) filaments.

Which of the following would not lead to aneuploidy during meiosis? (a) sister chromatids segregating inappropriately (b) non-sister chromatids segregating inappropriately (c) a reciprocal rearrangement of parts between nonhomologous chromosomes (for example, the left arm of Chromosome 2 exchanging places with the right arm of Chromosome 3) (d) an extra set of chromosomes produced during S phase (for example, if paternal Chromosome 3 were replicated twice)

Which type of junction involves a connection to the actin cytoskeleton? (a) adherens junctions (b) desmosomes (c) tight junctions (d) gap junctions

Which viruses contain cells? a) None of them b) All of them c) Some of them d) prokaryotes e) eukaryotes

You are interested in cell-size regulation and discover that signaling through a GPCR called ERC1 is important in controlling cell size in embryonic rat cells. The G protein downstream of ERC1 activates adenylyl cyclase, which ultimately leads to the activation of PKA. You discover that cells that lack ERC1 are 15% smaller than normal cells, while cells that express a mutant, constitutively activated version of PKA are 15% larger than normal cells. Given these results, which of the following treatments to embryonic rat cells should lead to smaller cells? (a) addition of a drug that causes cyclic AMP phosphodiesterase to be hyperactive (b) addition of a drug that prevents GTP hydrolysis by Gα (c) addition of a drug that activates adenylyl cyclase (d) addition of a drug that mimics the ligand of ERC1

______ couple the extracellular matrix to the cytoskeleton inside the animal cell. (a) Integrins (b) EGFRs (c) Cadherins (d) Beta-Catenins

______ produce the extracellular matrix of connective tissue. (a) Fibroblasts (b) Schwann cells (c) Macrophages (d) Blood vessels (e) Lymphocytes

_______ is called survival factor because it inhibits apoptosis by regulating members of the Bcl-2 family of proteins. (a) NGF (b) Akt (c) PKA (d) JAK

do you expect garlic to improve erections? a) Yes b) No c) There is no reason to think it will have any effect at all

will organize connctive tissues A. fibroblast B. Schwann cells C. macrophage d. blood vessels e. lymphocytes

Consider an animal cell that has eight chromosomes (four pairs of homologous chromosomes) in G1 phase. How many of each of the following structures will the cell have at mitotic prophase? A. sister chromatids B. centromeres C. kinetochores D. centrosomes E. centrioles

A-16 B-16 C-16 D-2 E-4

Of the following mutations, which are likely to cause cell-cycle arrest? If you predict a cell-cycle arrest, indicate whether the cell will arrest in early G1, late G1, or G2. Explain your answers. A. a mutation in a gene encoding a cell-surface mitogen receptor that makes the receptor active even in the absence of the mitogen B. a mutation that destroyed the kinase activity of S-Cdk C. a mutation that allowed G1-Cdk to be active independently of its phosphorylation status D. a mutation that removed the phosphorylation sites on the Rb protein E. a mutation that inhibited the activity of Rb

A-NO B-cell-cycle arrest in early G1 C-NO D-cell-cycle arrest in late G1 E-NO

Archaebacteria... a) are thought to be the first type of eukaryotic cell. b) do not have a nucleus. c) do not show metabolic activity. d) do not contain ribosomes. e) are primitive eukaryotic cells often found in extreme environments (like hot springs).

Name the stage of M phase in which the following events occur. Place the numbers 1-8 next to the letter headings to indicate the normal order of events. A. alignment of the chromosomes at the spindle equator B. attachment of spindle microtubules to chromosomes C. breakdown of nuclear envelope D. pinching of cell in two E. separation of two centrosomes and initiation of mitotic spindle assembly F. re-formation of the nuclear envelope G. condensation of the chromosomes H. separation of sister chromatids

A. 5, metaphase B. 4, prometaphase C. 3, prometaphase D. 8, cytokinesis E. 2, prophase F. 7, telophase G. 1, prophase H. 6, anaphase

Cells can pause in G1 when DNA is damaged, and can pause in S when there are replication errors. Indicate whether the mechanism below applies to a G1 arrest, an S-phase arrest, both types of arrest, or neither. A. p53 activates the transcription of a Cdk inhibitor. B. Cyclins are phosphorylated and destroyed. C. Cdk is unable to phosphorylate its substrates. D. The Cdc25 phosphatase is inhibited.

A. G1 arrest B. neither C. both D. S-phase arrest

At desmosomes, cadherin molecules are connected to ________________. (a) actin filaments. (b) intermediate filaments. (c) microtubules. (d) gap junctions.

Indicate whether the following molecules are found in plants, animals, or both. A. intermediate filaments B. cell walls C. microtubules D. cellulose E. collagen

A. animals B. plants C. both D. plants E. animals

What are the main structures providing tensile strength in the following? A. animal connective tissue B. animal epidermis C. plant cell walls

A. collagen fibers B. intermediate filaments C. cellulose fibers

Indicate whether each of the following is true for meiosis, mitosis, both, or neither. A. formation of a bivalent B. genetically identical products C. condensation of chromosomes D. segregation of all paternal chromosomes to one cell E. involvement of DNA replication

A. meiosis B. mitosis C. both D. neither E. both

) Which of the following is a functional cell unit of a muscle filament? a) sarcolemma b) sarcomere c) sarcoplasmic reticulum d) sarcoidosis

51) What is NOT a true statement about cell walls in prokaryotes? a) Cell walls help maintain the shape of the cell. b) All prokaryotes have cell walls. c) They help prevent the cell from undergoing osmotic lysis by reinforcing the cell against high intracellular water pressure pushing against the cell membrane. d) Bacterial cell walls are different from those of archea and eukaryotes because some contain peptidoglycan.

A bacterium is suddenly expelled from a warm human intestine into the cold world outside. Which of the following adjustments might the bacterium make to maintain the same level of membrane fluidity? (a) Produce lipids with hydrocarbon tails that are longer and have fewer double bonds. (b) Produce lipids with hydrocarbon tails that are shorter and have more double bonds. (c) Decrease the amount of cholesterol in the membrane. (d) Decrease the amount of glycolipids in the membrane.

A bacterium is suddenly expelled from a warm human intestine into the cold world outside. Which of the following adjustments might the bacterium make to maintain the same level of membrane fluidity? a) Produce lipids with hydrocarbon tails that are longer and have fewer double bonds. b) Produce lipids with hydrocarbon tails that are shorter and have more double bonds. c) Decrease the amount of cholesterol in the membrane. d) Decrease the amount of glycolipids in the membrane. e) Produce lipids with hydrocarbon tails that are short and saturated

A basal lamina ______________________. (a) is a thin layer of connective-tissue cells and matrix underlying an epithelium. (b) is a thin layer of extracellular matrix underlying an epithelium. (c) is attached to the apical surface of an epithelium. (d) separates epithelial cells from each other.

A cell with nuclear lamins that cannot be phosphorylated in M phase will be unable to ________________. (a) reassemble its nuclear envelope at telophase. (b) disassemble its nuclear lamina at prometaphase. (c) begin to assemble a mitotic spindle. (d) condense its chromosomes at prophase.

A diploid cell containing 32 chromosomes will make a haploid cell containing ___ chromosomes. (a) 8 (b) 16 (c) 30 (d) 64

A major distinction between the connective tissues in an animal and other main tissue types such as epithelium, nervous tissue, or muscle is _______________. (a) the ability of connective-tissue cells such as fibroblasts to change shape. (b) the amount of extracellular matrix in connective tissues. (c) the ability of connective tissues to withstand mechanical stresses. (d) the numerous connections that connective-tissue cells make with each other.

A pluripotent cell _________. (a) can only be produced in the laboratory. (b) can give rise to all the tissues and cell types in the body. (c) can only give rise to stem cells. (d) is considered to be terminally differentiated.

APC is a tumor suppressor and acts in the Wnt signaling pathway to prevent the TCF complex from turning on Wnt-responsive genes. Mice that lack the gene encoding TCF4 do not have the ability to maintain the pool of proliferating gut stem cells needed to renew the gut lining. What do you predict will happen in mice that lack the APC gene? (a) Mice lacking the APC gene will be like the mice lacking TCF4 and not be able to renew the gut lining. (b) Mice lacking the APC gene will have inappropriate proliferation of gut stem cells. (c) Mice lacking the APC gene will have a hyperactive Wnt receptor even though there is no Wnt signal. (d) Mice lacking the APC gene will be like normal healthy mice, since APC is a tumor suppressor and thus not needed unless there is a tumor present.

After the first meiotic cell division ________________________. (a) two haploid gametes are produced. (b) cells are produced that contain the same number of chromosomes as somatic cells. (c) the number of chromosomes will vary depending on how the paternal and maternal chromosomes align at the metaphase plate. (d) DNA replication occurs.

All of the following statements about the fluid mosaic model of biological membranes are true EXCEPT: (A) Lipid molecules in the membrane readily undergo lateral diffusion. (B) Lipid molecules in the membrane readily undergo transverse (flip-flop) diffusion. (C) Integral membrane proteins can undergo lateral diffusion. (D) The saturated hydrocarbon chains of lipid molecules in the membrane undergo carbon-carbon bond rotation. (E) The transition temperature of a membrane is sensitive to the composition of the lipid molecules in the membrane.

An individual that arises by reproductive cloning has a nuclear genome that is identical to __________. (a) the female who donated the egg. (b) the adult who donated the cell for nuclear transplantation. (c) both the female who donated the egg and the adult who donated the cell for nuclear transplantation. (d) the foster mother in which the embryo is placed.

Bcl2 family proteins... a) associate with integrins and the extracellular matrix. b) are intracellular mitochondrial-associated proteins that regulate apoptosis. c) bind to and activate CDK proteins. d) are a type of viral protein that causes leukemia. e) are inhibited by Herceptin.

CAK stands for __________. (a) Cytoplasmic Activating Kinase (b) Cdk Activating Kinase (c) Cytokinesis Activating Kinase (d) Cytokinesis Ablation Kinase

CDK proteins... a) tend to be suppressed in tumor cells. b) must associate with cyclin to be active. c) are caspase-dependent kinases. d) bind actin to form spindle fibers during mitosis. e) are a type of mitogen receptor.

Cadherins ______________________. (a) are used to transfer proteins from one cell to another. (b) mediate cell-cell attachments through homophilic interactions. (c) are abundant in the plant cell wall. (d) bind to collagen fibrils.

Cells that are terminally differentiated ______________________. (a) will undergo apoptosis within a few days. (b) can no longer undergo cell division. (c) are unable to move. (d) no longer produce RNAs.

Condensins ________________. (a) are degraded when cells enter M phase. (b) assemble into complexes on the DNA when phosphorylated by M-Cdk. (c) are involved in holding sister chromatids together. (d) bind to DNA before DNA replication begins.

Cultured fibroblasts were labeled with radioactive 32P-ortho-phosphate. Subsequent EGF treatment increased the radioactivity detected in a small subset of total cell proteins. Which of the following best explains this finding? a) EGF acts as a protein phosphatase b) EGF activates a protein kinase c) EGF activates an ATPase d) EGF is phosphorylated e) The activated receptor acts as a protein phosphatase

During recombination ________________________. (a) sister chromatids undergo crossing-over with each other. (b) chiasmata hold chromosomes together. (c) one crossover event occurs for each pair of human chromosomes. (d) the synaptonemal complex keeps the sister chromatids together until anaphase II.

Each of the following cell organelles have a membrane structure EXCEPT one. Which one is the EXCEPTION? A) Golgi comples B) Centrioles C) Mitochondria D) Lysosomes E) Endoplasmic reticulum

Ehlers-Danlos syndrome, a genetic disorder lacking collagenase which converts procollagen to collagen, will affect ____. (a) the basal lamina (b) connective tissue (c) stem cell maintenance (d) phagocytosis

Fermentation... a) produces pyruvic acid as an end product b) yields less energy per mole of glucose than aerobic respiration c) occurs only in the presence of oxygen d) prevents glycolysis from occurring e) converts ethanol to glucose

For many years, actin was thought to function only in the cytoplasm. In the last decade, it has become increasingly clear that actin also plays important roles in the nucleus, where it is important for chromatin remodeling, transcription, DNA replication, nuclear transport, and arrangement of chromosomes within the nucleus. This makes sense ¬- these processes require the rapid and coordinated movement of many molecules, which obviously don't just drift around the nucleus randomly. What other proteins do you think are most likely to have recently surprised scientists by being important in the nucleus? a) Laminins b) ARP2/3 c) Tau d) Nexins e) Kinesins

Gram stain is used to classify... a) Human tissue types b) Bacteria c) Chromosomes d) Organelles e) None of the above

Haplotype blocks can be seen in humans because _______. (a) disease genes are found in haplotype blocks. (b) modern humans descended from a relatively small population of about 10,000 individuals that existed about two thousand generations ago. (c) some of our human ancestors interbred with Neanderthals. (d) new mutations cannot be introduced into existing haplotype blocks.

Hexokinase activity in a desalted cell extract can be measured in a spectrophotometric assay at 340 nanometers. In addition to buffer, Mg2+, and lysate, the reation mixture should contain a) glucose, ATP, NADPH, and excess glucose 6-phosphate dehydrogenase b) glucose, ATP, NADP+, and excess glucose 6-phosphate dehydrogenase c) glucose, ADP, NADP+, and excess glucose 6-phosphate dehydrogenase d) glucose, ATP, NADP+, and excess 6-phosphogluconate dehydrogenase e) glucose 6-phosphate, ATP, NADP+, and excess glucose 6-phosphate dehydrogenase

If you crossed the round-seeded plants obtained in the F1 generation with a true-breeding strain of wrinkle-seeded plants, how many round-seeded plants would you expect to obtain in the next generation? (See Figure Q19-38.) (a) 25% (b) 50% (c) 75% (d) 100%

In mammals, there are two sex chromosomes, X and Y, which behave like homologous chromosomes during meiosis. Normal males have one X chromosome and one Y chromosome, and normal females have two X chromosomes. Males with an extra Y chromosome (XYY) are found occasionally. Which of the following could give rise to such an XYY male? Explain your answer. (a) nondisjunction in the first meiotic division of spermatogenesis; normal meiosis in the mother (b) nondisjunction in the second meiotic division of spermatogenesis; normal meiosis in the mother (c) nondisjunction in the first meiotic division of oogenesis; normal meiosis in the father (d) nondisjunction in the second meiotic division of oogenesis; normal meiosis in the father

In the late 1960s, a scientist named Howard Holtzer and his lab were using electron microscopy to study cultured muscle and fibroblast cells. They noticed a type of filament that was not as small as actin microfilaments (10 nm), and not as big as myosin filaments (15 nm). They named these filaments 'intermediate filaments'. Thus, contrary to what many students (and professors!) believe, intermediate filaments were NOT named because they were intermediate in size between actin filaments and microtubules. However, microtubules are indeed bigger than intermediate filaments - about 25 nM. What is the diameter of a single tubulin monomer? a) about 1 nm b) about 5 nm c) about 10 nm d) about 25 nm e) about 325 nm (25x13=325)

Living systems are incredibly diverse in size, shape, environment, and behavior. It is estimated that there are between 10 million and 100 million different species. Despite this wide variety of organisms, it remains difficult to define what it means to say something is alive. Which of the following can be described as the smallest living unit? (a) DNA (b) cell (c) organelle (d) protein

Making wine is easy. You just need a bunch of sugary grape juice (or any other sugary juice), and some yeast to convert the sugar to ethanol. The final fermentation needs to be done in the absence of oxygen (which is why you need to keep the bottles corked tightly!). Why? a) In the presence of oxygen, the yeast will not perform glycolysis and therefore oxidative phosphorylation will not occur and carbon dioxide will not be produced. You don't want too much carbon dioxide or the bottles will explode. b) In the presence of oxygen, yeast will break down pyruvate via the citric acid cycle instead of converting it to ethanol. c) If the presence of oxygen, yeast do not have sufficient carbon dioxide for electron transfer during the citric acid cycle. d) In the presence of oxygen, yeast preferentially burn fats instead of sugar. e) This is a trick question. Yeast would produce lactic acid in the absence of oxygen. Therefore you DO want oxygen so that sugars are broken down and NAD+ is regenerated.

Molecular Probes also sells a product called 'FM1-43', which is a fluorescent chemical that sticks to phospholipid bilayers. But it cannot cross lipid bilayers. If you put FM1-43 on the outside of a cell and waited, which of the following things do you think would happen? a) The plasma membrane would fluoresce, and then nothing else would fluoresce. b) The plasma membrane would fluoresce, then vesicles traveling retrograde, then the golgi. c) The ER would fluoresce first, then the golgi, then vesicles. d) Nothing would fluoresce, because FM1-43 cannot cross lipid bilayers.

Pili are short, thin fibers which protrude from the cell and serve a variety of functions. In pathogens, pili are considered a virulence factor. Which function of the pili explains this designation? a) Cell defense b) Adhesion c) Movement d) Signaling

Proteoglycans in the extracellular matrix of animal tissues ________________. (a) chiefly provide tensile strength. (b) allow cartilage to resist compression. (c) are linked to microtubules through the plasma membrane. (d) are polysaccharides composed of glucose subunits.

Retinoblastoma is a rare rapidly-developing type of retinal cancer that is associated with mutations in the Rb gene. Approximately half of all victims have inherited mutations in the Rb gene. These victims typically develop the disease in childhood. The other cases (termed 'sporadic retinoblastoma') are due to spontaneous mutations. The cure rate for retinoblastoma is among the highest of all cancers: 95-98%. Which of the following things is TRUE about Rb protein? a) Rb protein promotes apoptosis by triggering release of cytochrome C. b) Rb protein is inactivated when it is phosphorylated by active CDK. c) Rb protein is a type of growth factor receptor. d) Rb protein is a small GTPase. e) Rb protein forms a complex with other proteins to repair damaged DNA.

Retinoblastoma is a target of mitogen. What is the function of Rb? a. activates b. inhibitor E2F c. activates Myc D. inhibits Myc

Ribosomes are mostly associated with... a) The nucleus b) The endoplasmic reticulum c) The rough golgi d) The peroxisomes e) Dexoyribonucleic acid

Saturated fatty acids... a) Contain less hydrogen than unsaturated fatty acids b) Contain no double or triple carbon-carbon bonds c) Tend to have lower melting temperatures d) Have a polar phosphate group e) are amphipathic

Scar tissue is secreted primarily by fibroblasts. What is scar tissue mostly made of? a) keratin b) collagen c) intermediate filaments d) cellulose e) stem cells

Scientists have hypothesized that mitochondria evolved from aerobic heterotrophic bacteria that entered and established symbiotic relationships with primitive eukaryotic anaerobes. According to this hypothesis, the bacteria that entered primitive eukaryotic cells were able to carry out which functions) that the primitive eukaryotic cells could not? a) Glycolysis b) Krebs cycle and electron transport c) Cell division d) Transcription and translation

Sodium nitrite is added to processed meats (mainly bacon, hot dogs, etc). Nitrite is a preservative (it inhibits bacterial growth) and also enhances the meat's color and taste. Unfortunately, nitrites are converted to nitrosamines during digestion. Nitrosamines are highly carcinogenic, because most amine chemicals are mutagens (they cause mutations). Imagine that a parietal cell is exposed to nitrosamines, becomes mutated, and proliferates into a tumor that is 3 cm in diameter. Which of the following is likely TRUE? a) Nitrosamines trigger apoptosis. b) The parietal cell probably has a mutation in the P53 gene. c) The stomach lining may start expressing GFP. d) The mutant parietal cells secrete less VEGF. e) All of the above.

Sodium nitrite is added to processed meats (mainly bacon, hot dogs, etc). Nitrite is a preservative (it inhibits bacterial growth) and also enhances the meat's color and taste. Unfortunately, nitrites are converted to nitrosamines during digestion. Nitrosamines are highly carcinogenic, because most amine chemicals are mutagens (they cause mutations). Imagine that a parietal cell is exposed to nitrosamines, becomes mutated, and proliferates into a tumor that is 3 cm in diameter. Which of the following is likely TRUE? a) The stomach will become less acidic. b) The parietal cell probably has a mutation in the P53 gene. c) There will be less CCK2 protein in the stomach. d) The mutant parietal cells secrete less VEGF. e) All of the above.

TeloVac is a new vaccine that just recently (April 2011) entered clinical trials for pancreatic cancer in the United Kingdom. Pancreatic cancer has the worst survival rate of any cancer. Any treatment that could help would be extremely valuable. Telovac is a vaccine against telomerase, which many tumor cells tend to overexpress and display on their cell surface. It is hoped that the immune systems in patients vaccinated with TeloVac will attack tumor cells. Telomerase is an enzyme that replaces telomeres. Unless telomeres are replaced, a cell can undergo only a limited number of rounds of DNA replication. Which of the following might be an expected side effect of this vaccine? a) Increased angiogenesis leading to internal bleeding b) Loss of stem cells (causing, for example, gastrointestinal problems, hair loss, or loss of blood cells) c) Increased mutation rates, leading to more cancers d) Insensitivity to morphogens, such that tissues do not develop correctly e) Increased signaling in contact inhibition pathways, such that wounds do not heal

TeloVac is a new vaccine that recently (April 2011) entered clinical trials for pancreatic cancer in the United Kingdom. Pancreatic cancer has the worst survival rate of any cancer. Any treatment that could help would be extremely valuable. Telovac is a vaccine against telomerase, which many tumor cells tend to overexpress and display on their cell surface. It is hoped that the immune systems in patients vaccinated with TeloVac will attack tumor cells. Telomerase is an enzyme that replaces telomeres. Unless telomeres are replaced, a cell can undergo only a limited number of rounds of DNA replication. Which of the following might be an expected side effect of this vaccine? a) Increased angiogenesis leading to internal bleeding b) Loss of stem cells (causing, for example, gastrointestinal problems, hair loss, or loss of blood cells) c) Increased mutation rates, leading to more cancers d) Insensitivity to morphogens, such that tissues do not develop correctly e) Increased signaling in contact inhibition pathways, such that wounds do not heal

The Oreck vacuum cleaner company advertises that their 'hypoallergenic filters' remove anything larger than 0.3 microns. Which of the following would be effectively caught by Oreck's filters? a) Viruses b) Bacteria c) ATP d) Antibodies e) More than one of the above

The carbon dioxide that people exhale is a waste product of metabolism. Where does this CO2 come from? a) The oxygen that people inhale is combined with carbon from the breakdown of foods like glucose. b) Carbon from food is combined with oxygen from water during the tricarboxylic acid cycle. c) Carbon from pyruvate is combined with oxygen during oxidative phosphorylation. d) Carbon dioxide is produced from the hydrolysis of ATP. e) CO2 acts as the final electron acceptor at the end of the electron transport chain.

The cartoon above refers to the ethical debate concerning use of embryonic stem cells. Which of the following might be a biomedically useful substitute for embryonic stem cells? a) Cytokines b) Induced pluripotent stem cells c) Morphogens d) Bone marrow e) Cell differentiation

The diagram to the right shows the cellulose synthase complex. Which of the following is TRUE? a) Cellulose is a polymer of fructose. b) Cellulose is a component of the extracellular matrix. c) Cellulose synthase synthesizes collagen. d) Sucrose synthase is a mitochondrial protein. e) Cellulose is secreted via SNARE-dependent exocytosis.

The formation of a bivalent during meiosis ensures that _______. (a) one chromatid from the mother and one chromatid from the father will segregate together during meiosis I. (b) all four sister chromatids remain together until the cell is ready to divide. (c) recombination will occur between identical sister chromatids. (d) the sex chromosomes, which are not identical, will line up separately at the metaphase plate during meiosis I.

The human microbiome consists mostly of... a) archaea b) bacteria c) eukaryotic cells d) types of fungus e) organelles

The most common form of diabetes is Type II diabetes. The number of people with Type II diabetes in the U.S. has doubled over the past 15 years. Approximately 8% of the U.S. population now has type II diabetes. In type II diabetes, pancreatic beta cells produce insulin, but other cell types do not respond very well to this insulin. Most often, type II diabetes results from chronically high blood glucose. Type II diabetes is strongly associated with obesity. Which of the following drugs is most likely to help type II diabetics? a) Synthetic glucagon b) Metformin, which suppresses gluconeogenesis (glucose synthesis) in the liver c) BW-414X, a glucose transporter inhibitor d) Firplakinolide, a drug that increases transport of glucose transporters to lysosomes e) CK0106023, a kinesin inhibitor that suppresses movement of secretory vesicles

The movement of sodium ions into a cell typically involves _____________, but moving them back out again is often done via _____________. a) passive transport, calcium channels b) channels, active transport c) antiporters, sodium-potassium pumps d) SNARE proteins, clathrin e) Sodium pumps, diffusion

The nucleus, an organelle found in eucaryotic cells, confines the __________, keeping them separated from other components of the cell. a) lysosomes b) chromosomes c) peroxisomes d) ribosomes e) phospholipids

The nucleus, an organelle found in eukaryotic cells, confines the __________, keeping them separated from other components of the cell. (a) lysosomes (b) chromosomes (c) peroxisomes (d) ribosomes

The oxygen generated during photosynthesis comes from... a) carbon dioxide b) water c) glucose d) transfer of electrons to NAD+ e) anaerobic respiration

The regulatory component of MPF, called Cyclin, will be Ubiquitylated by _______ . (a) PI3K (b) APC (c) p53 (d) cyclin

The rough endoplasmic reticulum is so named because of ribosomes on its membrane. Which of the following statements best describes the way in which these ribosomes translate proteins? A From the cytosol, into the intermembrane space of the endoplasmic reticulum B From the cytosol, into the lumen of the endoplasmic reticulum C From the intermembrane space of the endoplasmic reticulum, into the cytosol D From the lumen of the endoplasmic reticulum, into the cytosol

The three major classes of lipids found in cells are... a) Phospholipids, sphingolipids, and cholesterol b) Phospholipids, sterols, and glycolipids c) Fatty acids, hydrophilic head groups, and ethanolamines d) Phosphatidylserines, cholesterols, and galactocerebrosides e) Fatty acids, sugars, alcohols

There are two properties of phospholipids that affect how tightly they pack together: the length of the hydrocarbon chain and the number of double bonds. The degree of packing, in turn, influences the relative mobility of these molecules in the membrane. Which of the following would yield the most highly mobile phospholipid (listed as number of carbons and number of double bonds, respectively)? (a) 24 carbons with 1 double bond (b) 15 carbons with 2 double bonds (c) 20 carbons with 2 double bonds (d) 16 carbons with no double bonds

There are two properties of phospholipids that affect how tightly they pack together: the length of the hydrocarbon chain and the number of double bonds. The degree of packing, in turn, influences the relative mobility of these molecules in the membrane. Which of the following would yield the most highly mobile phospholipid listed as number of carbons and number of double bonds, respectively)? a) 24 carbons with 1 double bond b) 15 carbons with 2 double bonds c) 20 carbons with 2 double bonds d) 16 carbons with no double bonds e) 13 carbons with no double bonds

Viagra promotes erections. How? a) Viagra is a guanylyl cyclase inhibitor b) Viagra inhibits cGMP phosphodiesterase c) Viagra inhibits nitric oxide synthase d) Viagra inhibits Akt signaling e) Viagra inhibits heterotrimeric G proteins

We were taught in the class of Bios222 that cancer is a disease which is caused by the accumulations of different mutations. Which of the following statement(s) is true, and can increase the risk of getting cancer? a) A mutation in the RasGTP protein complex which prevents Ras from hydrolyzing GTP to GDP which under activates Raf and eventually leads to the uncontrolled cell proliferation. b) A viral infection that produces a protein which can inhibit the promoter p53 which is responsible of inhibiting the cell cycle when DNA is damage. c) A mutation in the genes Keratin K5 and K4 which causes the intermediate filaments found in the skin not to assemble correctly which leads to a condition called Epidermolysis bullosa Simplex. d) All of the statements are true and increased the risk of cancer. e) Only, B and C are true and increase the risk of cancer.

What is the most common type of protein in a cell? a) Membrane proteins b) Ribosomal proteins c) Nuclear proteins d) Water e) DNA

Where do TCA cycle reactions take place? a) In the cytoplasm. b) In mitochondria. c) In chloroplasts. d) In the nucleus. e) In the ER

Where do TCA cycle reactions take place? a) In the cytoplasm. b) In mitochondria. c) In chloroplasts. d) In the nucleus. e) In the ER.

Where does most new membrane synthesis take place in a eucaryotic cell? a) in the Golgi apparatus b) in the endoplasmic reticulum c) in the plasma membrane d) in the mitochondria e) on ribosomes

Which of the following best describes the role of NAD+/NADH in metabolism? a) NADH is used to produce energy by catalyzing the formation of phosphoanhydride bonds in ATP. b) NAD+ is used to carry electrons. c) NADH transfers electrons across membranes. d) NADH is converted to pyruvate, which enters the citric acid cycle. e) NAD+ catalyzes the first step in breakdown of glucose.

Which of the following cells do NOT have a cell wall? a) Prokaryotic b) Animal c) Plant d) Bacteria e) All of the above have a cell wall

Which of the following choices best describes the role of the lysosome? (a) transport of material to the Golgi (b) clean-up, recycling, and disposal of macromolecules (c) sorting of transport vesicles (d) the storage of excess macromolecules

Which of the following could be considered a true-breeding strain for the seed-shape phenotype? (See Figure Q19-38.) (a) all of the round-seeded plants produced in the F2 generation (b) all of the wrinkle-seeded plants produced in the F2 generation (c) all of the round-seeded plants produced in the F1 generation (d) half of the round-seeded plants produced in the F2 generation

Which of the following is CORRECT? a) Dynein moves toward the plus (+) end of microtubules b) Dynein is a 'motor MAP' c) Dynein moves toward the plus (+) end of actin filaments d) Dynein's assembly can be inhibited with nocodazole e) Dynein 'walks' along the microfilament to cause sarcomere shortening

Which of the following is CORRECT? a) ARP 2/3 nucleates assembly of tubulin dimers b) The mechanism of flagellar movement differs between prokaryotes and eukaryotes c) Collagen is a type of intermediate filament d) Muscle thin filaments are made of actin and thick filaments are made of tubulin e) Pectin is an extracellular matrix protein secreted by fibroblasts

Which of the following is CORRECT? a) Plasmodesmata are made up of gap junctions b) The endoplasmic reticulum of one cell can extend into another cell through plasmodesmata; the portion of the ER that does this is called a 'desmotubule' c) Charged molecules such as calcium or sodium cannot pass through plasmodesmata d) Plasmodesmata bind calcium during muscle contraction e) Actors have actin but carrots have keratin

Which of the following is MOST LIKELY to be an effective cancer treatment? a) An inhibitor of caspases b) An inhibitor of VEGF c) A growth factor d) All of the above e) None of the above

Which of the following is NOT an actin-binding protein? a) CapZ b) MAP4 c) Myosin d) Tropomyosin e) Alpha-actinin

Which of the following is TRUE? a) Vesicles are carried from the cis golgi to the trans golgi (toward the cell periphery) by kinesins moving along microtubules b) A drug that binds to and blocks the myosin head binding site on actin would likely disrupt cell division c) Drugs that disrupt actin filaments typically disrupt the organization of the golgi apparatus d) Intermediate filament shortening leads to smooth muscle contraction e) Motor MAPs move organelles and vesicles along actin filaments near the cell membrane

Which of the following is a functional cell unit of a muscle filament? a) sarcolemma b) sarcomere c) sarcoplasmic reticulum d) sarcoidosis

Which of the following is a second messenger that stimulates release of calcium ions into the cytoplasm? a) Prostaglandins b) Inositol triphosphate c) Cyclic AMP d) Calmodulin

Which of the following statements about tumor suppressor genes is false? (a) Gene amplification of a tumor suppressor gene is less dangerous than gene amplification of a proto-oncogene. (b) Cells with one functional copy of a tumor suppressor gene will usually proliferate faster than normal cells. (c) Inactivation of tumor suppressor genes leads to enhanced cell survival and proliferation. (d) Individuals with only one functional copy of a tumor suppressor gene are more prone to cancer than individuals with two functional copies of a tumor suppressor gene.

Which of the following statements is TRUE? a) Necrosis is the first stage of apoptosis. b) adenylate cyclase synthesizes cyclic adenosine monophosphate. c) Apoptosis is triggered by active CDK. d) Caspases are kinases. e) Caspases cause polyubiquitination of cyclin.

Which of the following statements is false? (a) Asexual reproduction typically gives rise to offspring that are genetically identical. (b) Mutations in somatic cells are passed on to individuals of the next generation. (c) Sexual reproduction allows for a wide variety of gene combinations. (d) Gametes are specialized sex cells.

Which of the following statements is false? (a) DNA synthesis begins at origins of replication. (b) The loading of the origin recognition complexes (ORCs) is triggered by S-Cdk. (c) The phosphorylation and degradation of Cdc6 help to ensure that DNA is replicated only once in each cell cycle. (d) DNA synthesis can only begin after prereplicative complexes assemble on the ORCs.

Which of the following statements is true? (a) Because endocrine signals are broadcast throughout the body, all cells will respond to the hormonal signal. (b) The regulation of inflammatory responses at the site of an infection is an example of paracrine signaling. (c) Paracrine signaling involves the secretion of signals into the bloodstream for distribution throughout the organism. (d) The axons of neurons typically signal target cells using membrane-bound signaling molecules that act on receptors in the target cells.

Which organelle fragments during mitosis? (a) endoplasmic reticulum (b) Golgi apparatus (c) mitochondrion (d) chloroplast

Which statement is NOT true about the events/conclusions from studies during the mid-1800s surrounding the discovery of cells? (a) Cells came to be known as the smallest universal building block of living organisms. (b) Scientists came to the conclusion that new cells can form spontaneously from the remnants of ruptured cells. (c) Light microscopy was essential in demonstrating the commonalities between plant and animal tissues. (d) New cells arise from the growth and division of previously existing cells.

You are trying to develop a drug that will inhibit metastasis. Which of the following types of drugs is LEAST likely to inhibit epithelial tumor metastasis? a) A drug that decreases epithelial cell motility. b) A drug that decreases epithelial cell adhesion. c) A drug that decreases the ability of epithelial cells to secret proteases. d) A drug that inhibits the secretion of VEGF. e) A drug that increases the ability of epithelial cells to be recognized by the immune system.

You are trying to develop a drug that will inhibit metastasis. Which of the following types of drugs is most likely to inhibit epithelial tumor metastasis? a) A drug that increases epithelial cell motility. b) A drug that increases epithelial cell adhesion. c) A drug that increases the ability of epithelial cells to secret proteases. d) A drug that promotes the secretion of VEGF. e) A drug that inhibits the ability of epithelial cells to be recognized by the immune system.

You create cells with a version of Cdc6 that cannot be phosphorylated and thus cannot be degraded. Which of the following statements describes the likely consequence of this change in Cdc6? (a) Cells will enter S phase prematurely. (b) Cells will be unable to complete DNA synthesis. (c) The origin recognition complex (ORC) will be unable to bind to DNA. (d) Cdc6 will be produced inappropriately during M phase.

You have isolated a strain of mutant yeast cells that divides normally at 30°C but cannot enter M phase at 37°C. You have isolated its mitotic cyclin and mitotic Cdk and find that both proteins are produced and can form a normal M-Cdk complex at both temperatures. Which of the following temperature-sensitive mutations could not be responsible for the behavior of this strain of yeast? (a) inactivation of a protein kinase that acts on the mitotic Cdk kinase (b) inactivation of an enzyme that ubiquitylates M cyclin (c) inactivation of a phosphatase that acts on the mitotic Cdk kinase (d) a decrease in the levels of a transcriptional regulator required for producing sufficient amounts of M cyclin

________ is a kinase that inhibit M-Cdk. (a) Cdc25 (b) Wee1 (c) Abl (d) Chk1

n a time when therapeutic cloning of humans is a legal and common practice, it is possible for a man with androgenic alopecia, male pattern baldness caused by genetic mutation in maternal X chromosome, to grow hair using therapeutic cloning. Using our knowledge of therapeutic cloning which would be the most successful way for cloning so the man could grow hair. a) Take embryonic stem cells from the patient and clone the new embryo b) Genetically alter the DNA to fix the mutation in the patient's embryonic stem cell and clone the new embryo c) Take a hair follicle cell from the patient and use it to clone a new embryo d) Use hair follicle cells from the patient and make induced pluripotent stem cells e) None of the above

the cytoplasm splits in two in a process called __________________. a. condensation b. cytokinesis c. mitosis d. fission

will provide electrical insulation for axons A. fibroblast B. Schwann cells C. macrophage d. blood vessels e. lymphocytes

Irradiated mammalian cells usually stop dividing and arrest at a G1 checkpoint. Place the following events in the order in which they occur. A. production of p21 B. DNA damage C. inhibition of cyclin-Cdk complexes D. accumulation and activation of p53

B, D, A, C

. Studies with Xenopus eggs identified a partly purified activity called MPF that drives a resting Xenopus oocyte into M phase. MPF stands for _____. (a) Mitosis Prevention Factor (b) Mitotic Phase Filament (c) Maturation Promoting Factor (d) Maturation Prevention Factor

In anaerobic glycolysis in muscle cells, one mole of glucose is oxidized to... a) six moles of carbon dioxide b) two moles of acetic acid c) two moles of lactic acid d) two moles of acetyl CoA e) two moles of carbon dioxide and six moles of water

A patient enters the emergency room suffering from hypoxia (lack of oxygen). Which of the following is the expected metabolic outcome for this patient under these conditions? a) increased ATP production b) decreased lactic acid production c) increased lactic acid production d) decreased rate of pyruvate production

A previously unknown organism that lacks a nuclear membrane and mitochondria has just been discovered. Which of the following would this organism most likely possess? (A) Lysosomes (B) Cilia (C) Ribosomes (D) Endoplasmic reticulum (E) Chloroplasts

A receptor ligand that does not elicit a biological response but binds to a receptor and blocks other molecules from eliciting responses is called a) ligand antagonist b) ligand agonist c) receptor antagonist d) receptor agonist

After receiving a patient's test results, a physician notices that the patient has a mutation in his or her Rb protein. The physician knows that the patient is at risk for cancer as a result of this mutation. Which of the following is the correct path that led the physician to reach this conclusion? a) A mutation in Rb proteins → inhibits gene transcription → puts a stop to cell division → prevents cell proliferation → tumor formation → cancer b) A mutation in Rb proteins → prevents the phosphorylation of GDP → cell has constant interaction with Raf → constant cell proliferation → tumor formation → cancer c) A mutation in Rb proteins → promotes gene transcription → increases cell division → causes cell proliferation → tumor formation → cancer d) A mutation in Rb proteins → promotes dephosphorylation of GTP → cell has constant interaction with Raf → prevents cell proliferation → tumor formation → cancer e) A mutation in Rb proteins → causes cell membrane growth → decreases cell division → constant cell proliferation → tumor formation → cancer

After transport through the bloodstream, testosterone enters cells and binds to androgen receptor proteins that are in the cell cytoplasm. Which organelle is the primary location for androgen receptor protein synthesis? a) Smooth endoplasmic reticulum b) Rough endoplasmic reticulum c) Ribosomes d) Mitochondria e) Nucleus

All of the following statements about monomeric G proteins are true EXCEPT: (A) They are regulated by GTP-GDP exchange proteins. (B) They are regulated by GTPase activating proteins. (C) They regulate enzymes that synthesize cGMP . (D) They regulate vesicle formation. (E) They regulate vesicle fusion.

In respiration, most ATP is produced... a) during glycolysis. b) in the citric acid cycle. c) during oxidative phosphorylation. d) in fermentation. e) by tubulin dimers

An adult hemopoietic stem cell found in the bone marrow ______________________. (a) will occasionally produce epidermal cells when necessary. (b) can produce only red blood cells. (c) can undergo self-renewing divisions for the lifetime of a healthy animal. (d) will express all the same transcription factors as those found in an unfertilized egg.

Apoptosis differs from necrosis in that necrosis ________________. (a) requires the reception of an extracellular signal. (b) causes DNA to fragment. (c) causes cells to swell and burst, whereas apoptotic cells shrink and condense. (d) involves a caspase cascade.

At the end of DNA replication, the sister chromatids are held together by the ___________. (a) kinetochores. (b) securins. (c) cohesins. (d) histones.

Brain cells (neurons) and liver cells (hepatocytes) in a given person have different functions despite containing the same genetic information. Which of the following is the best explanation for this: a) Each cell has access to different amino acids; therefore, each cell produces different proteins. b) Each cell has missing portions of DNA that the other cell has; therefore, each cell produces different proteins. c) Each cell has genes that have been turned OFF that are different from the other cell; therefore, each cell produces different proteins. d) Each cell has the same functions that the cell surrounding it have

Cancer cells grown in culture are similar to normal cells grown in culture in that they a) divide an indefinite number of times b) do not display contact inhibition c) require oxygen and nutrients d) proliferate to the same cell density e) require similar levels of growth factors for proliferation

Cancers that arise from alterations in bone marrow stem cell development are a type of... a) carcinoma b) sarcoma c) leukemia d) lymphoma e) stem cell

Cells which can develop into any type of tissue in an organism are called... a) multipotent stem cells b) pluripotent stem cells c) totipotent stem cells d) iPS cells e) hematopoietic stem cells

Centrosomes... a) are composed of microfilaments. b) promote microtubule instability. c) are microtubule organizing centers. d) are composed of intermediate filament proteins, such as nuclear lamins. e) are regulated by Arp2/3.

Crystallography is a visualization technique to determine the arrangement of atoms in solids. It has been incredibly useful in discovering the structures of many proteins, such as hemoglobin. Difficulties arise when crystallography is attempted on non-polar molecules, such as proteins high in valine or alanine. Using this information, which of the following would be most difficult to visualize using crystallography? A A ribosome B A viral protein from HIV C A transmembrane protein D A digestive protease

Desmosomes are associated most with which type of cytoskeletal protein? a) Actin b) Microtubules c) Intermediate filaments d) Connexin e) None of the above

During cytokinesis in an animal cell, a constricting ring pinches the dividing cell into two daughter cells. This contractile ring is formed by which of the following structures? a) centrioles b) microtubules c) microfilaments d) Z discs e) The spindle apparatus

During development, retinoic acid plays an important role in development control. Excess of this type of Vitamin A can cause phenotypic abnormalities such as ear malformations or cleft palate. Retinoic acid is generally known as a teratogen, which are basically things that cause birth defects because they can act as___________ in developing tissue. a) Pluripotent stem cells b) Macrophages c) Morphogens d) Totipotent stem cells e) Erythrocytes

During the cel cylcle, the nucleus divides in a porcess called? a. condensation b. cytokinesis c. mitosis d. fission

Finding co-inheritance of a SNP variant and a disease tells scientists that ____________________. (a) everybody who carries this SNP will get the disease. (b) sequences within the SNP cause the disease. (c) a gene important for causing the disease is linked to the SNP. (d) SNPs on other chromosomes will not be co-inherited with the disease.

Gamma-aminobutyric acid-A (GABA-A) receptors are GABA-gated chloride channels. They are found in the plasma membrane of certain types of neurons. Which of the following is TRUE? a) GABA-A receptors are synthesized by ribosomes in the nucleus. b) GABA is a steroid hormone. c) When GABA-A receptors are being synthesized, their ligand-binding site is inside the lumen of the ER. d) Benzodiazepines reduce chloride flow through the plasma membrane. e) GABA-A receptors have seven transmembrane segments.

Hematopoietic stem cells differentiate into blood cells. If you were to compare the stem cells to the differentiated blood cells, which of the following would you most likely find to be TRUE? a) The hematopoietic stem cells have very few membrane receptors, relative to blood cells. b) The hematopoietic stem cells are slowly proliferating, relative to blood cells. c) The hematopoietic stem cells are expressing different genes compared to blood cells. d) The hematopoietic stem cells are terminally differentiated, compared to blood cells. e) The hematopoietic stem cells contain more DNA mutations, compared to blood cells.

How does S-Cdk help guarantee that replication occurs only once during each cell cycle? (a) It blocks the rise of Cdc6 concentrations early in G1. (b) It phosphorylates and inactivates DNA helicase. (c) It phosphorylates the Cdc6 protein, marking it for destruction. (d) It promotes the assembly of a prereplicative complex.

How many viruses could fit inside the (empty) plasma membrane of a typical prokaryotic cell? a) Not even one; viruses are about the same size as prokaryotes b) Maybe one or two c) A lot! Probably at least a few hundred, maybe thousands or more! d) Viruses ARE prokaryotes e) Zero, because prokaryotic cells don't have plasma membranes

Intermediate filaments... a) are a component of sarcomeres b) are the 'thick filament' in skeletal muscle cells c) are a type of cytoskeletal protein with a diameter about 8-10 nanometers. d) interact with myosin to drive cytokinesis e) are important components of flagella and cilia

Kinesin, dynein, and myosin... a) bind to microtubules. b) bind to actin. c) bind and hydrolase ATP to ADP. d) are motor MAPs. e) are found only in animal cells.

Many textbooks, especially older ones editions or textbooks that are not updated frequently, and some websites, say that bacteria do not have a cytoskeleton. This is incorrect. It's just that the proteins that make up the bacterial cytoskeleton are different in amino acid sequence and slightly different in function. But ultimately, many bacterial cytoskeletal proteins have been shown to have similar structure and roles in the cell. "Filamentation temperature-sensitive protein Z (FtsZ)" is a key player in bacterial cell division and binds and hydrolyzes GTP. In 1998, J. Löwe & L. A. Amos published a paper: "Crystal structure of the bacterial cell-division protein FtsZ" (Nature 391, 203-206, 1998). Löwe and Amos discovered that FtsZ looked a lot like a well-known vertebrate protein. Which of the following vertebrate proteins does FtsZ look like? a) actin b) keratin c) tubulin d) kinesin e) a heterotrimeric G-protein

Medullary thyroid carcinoma is a type of thyroid cancer that occurs in the parafollicular cells. Which of the following can be used as a tumor marker in order to identify medullary carcinoma? a) thyroid hormone b) cell membrane receptors c) abnormal rate of cell division d) epidermal growth factor

Mice lacking a functional plectin gene die within a few days of birth, with blistered skin and abnormal skeletal and heart muscles (with disruption of skin keratin, muscular dystrophy and disruption of neurofilaments). Which is the most likely definition of the main use of plectin? a) Plectin is a protein that carries intracellular messages to and fro. b) Plectin is in charge of maintaining the appropriate concentration of Na+/K+. c) Plectin is a protein that links intermediate filaments to microtubules, to actin filaments and to desmosomes. d) Plectin is a protein that controls the disassembly and reassembly of the mitotic spindle. e) None of the above

Most proteins destined to enter the endoplasmic reticulum _________. (a) are transported across the membrane after their synthesis is complete. (b) are synthesized on free ribosomes in the cytosol. (c) begin to cross the membrane while still being synthesized. (d) remain within the endoplasmic reticulum.

Pick the BEST answer: Phalloidin is a drug that binds to and stabilizes actin filaments. Which of the following do you think phalloidin would primarily disrupt? a) Flagellar movement b) Skeletal muscle contraction c) Cell 'crawling' using filopodia and lamellipodia d) Epithelial cell strength and structure e) Protofilament assembly

Protein glycosylation in eukaryotic proteins is associated with which organelle? A Mitochondria B Nucleus C Golgi apparatus D Ribosome

Ras is a GTP-binding protein that is often defective in cancer cells. A common mutation found in cancer cells causes Ras to behave as though it were bound to GTP all the time, which will cause cells to divide inappropriately. From this description, the normal Ras gene is _______. (a) a tumor suppressor. (b) an oncogene. (c) a proto-oncogene. (d) a gain-of-function mutation.

Signal sequences that direct proteins to the correct compartment are _________. (a) added to proteins through post-translational modification. (b) added to a protein by a protein translocator. (c) encoded in the amino acid sequence and sufficient for targeting a protein to its correct destination. (d) always removed once a protein is at the correct destination.

Somatic cells ___________________________. (a) are not necessary for sexual reproduction in all eukaryotic organisms. (b) are used to produce germ-line cells when organisms reach sexual maturity (c) leave no progeny. (d) do not contain sex chromosomes

Some cosmetics include inhibitors of lactic acid dehydrogenase, which reduces anaerobic glycolysis. This apparently promotes keratinocyte (skin) cell proliferation and collagen synthesis, making people who use these cosmetics look better. Which of the following would be TRUE about cells exposed to lactic acid dehydrogenase inhibitors? a) They cannot metabolize glucose; thus most energy must be produced by breakdown of things like fatty acids, which enter the core metabolic reactions via the citric acid cycle. b) They preferentially produce lactic acid instead of pyruvate, during glycolysis. c) They cannot regenerate NAD+ in the absence of oxygen, and glycolysis shuts down due to lack of an electron acceptor in the absence of NAD+. d) All of the cellular ATP is produced via oxidative phosphorylation. e) The cells would show increased conversion of pyruvate to ethanol.

The Retinoblastoma (Rb) protein blocks cells from entering the cell cycle by ______. (a) phosphorylating Cdk. (b) marking cyclins for destruction by proteolysis. (c) inhibiting cyclin transcription. (d) activating apoptosis.

The concentration of mitotic cyclin (M cyclin) ________________. (a) rises markedly during M phase. (b) is activated by phosphorylation. (c) falls toward the end of M phase as a result of ubiquitylation and degradation. (d) is highest in G1 phase.

The endoplasmic reticulum is, by weight, approximately 10% ... a) Lipid b) Protein c) Carbohydrate d) Nucleic acid e) Rubber

The epidermis (skin) is renewed from ________. (a) differentiated keratinocytes migrated from the other part of the body (b) totipotent stem cells from the bone marrow in its basal layer (c) pluripotent stem cells in its basal layer (d) pluripotent stem cells migrated from the other part of the body

The following happens when a G-protein-coupled receptor activates a G protein. (a) The β subunit exchanges its bound GDP for GTP. (b) The GDP bound to the α subunit is phosphorylated to form bound GTP. (c) The α subunit exchanges its bound GDP for GTP. (d) It activates the α subunit and inactivates the βγ complex.

The growth factor Superchick stimulates the proliferation of cultured chicken cells. The receptor that binds Superchick is a receptor tyrosine kinase (RTK), and many chicken tumor cell lines have mutations in the gene that encodes this receptor. Which of the following types of mutation would be expected to promote uncontrolled cell proliferation? (a) a mutation that prevents dimerization of the receptor (b) a mutation that destroys the kinase activity of the receptor (c) a mutation that inactivates the protein tyrosine phosphatase that normally removes the phosphates from tyrosines on the activated receptor (d) a mutation that prevents the binding of the normal extracellular signal to the receptor

The lab you work in has discovered a previously unidentified extracellular signal molecule called QGF, a 75,000-dalton protein. You add purified QGF to different types of cells to determine its effect on these cells. When you add QGF to heart muscle cells, you observe an increase in cell contraction. When you add it to fibroblasts, they undergo cell division. When you add it to nerve cells, they die. When you add it to glial cells, you do not see any effect on cell division or survival. Given these observations, which of the following statements is most likely to be true? (a) Because it acts on so many diverse cell types, QGF probably diffuses across the plasma membrane into the cytoplasm of these cells. (b) Glial cells do not have a receptor for QGF. (c) QGF activates different intracellular signaling pathways in heart muscle cells, fibroblasts, and nerve cells to produce the different responses observed. (d) Heart muscle cells, fibroblasts, and nerve cells must all have the same receptor for QGF.

The level of active mitotic CDK rises and falls during the cell cycle. Which of the following best explains why the levels of active mitotic CDK rise? a) Cyclin is degraded by APC, removing MPF inhibition b) Active MPF that already exists in the cell stimulates APC, which phosphorylates cyclin c) New cyclin is produced, binds CDK, and then undergoes a series of phosphorylation and dephosphorylation reactions to generate active CDK d) Checkpoint proteins trigger a MAP kinase cascade which activates transcription factors such as jun, that promote transcription of CDK protein. e) Lots of things rise. For example, the sun rises every morning, bread rises during cooking, and vampires rise from their graves. CDK basically works the same way as these things. It's best not to question why.

The plasmodesmata in plants are functionally most similar to which animal cell junction? (a) tight junction (b) adherens junction (c) gap junction (d) desmosome

The single-nucleotide polymorphisms found in the human population __________________. (a) are important for genetic mapping because they represent mutations in genes important for human disease. (b) are rarely found among blood relatives. (c) can be linked into haplotype blocks. (d) arose mainly during the past 10,000 years.

The sodium-potassium pump is an example of... a) passive transport b) an ion channel c) active transport d) coupled transport e) a voltage-gated ion channel

The source of oxygen for O2 production during photosynthesis by higher plants is a) CO2 b) HCO3- c) H2O d) ATP e) chlorophyll

There are organisms that go through meiosis but do not undergo recombination when forming haploid gametes. Which of the following statements correctly describes the gametes produced by such an organism. (Assume that these organisms are diploid, that each of the two homologous chromosomes are genetically distinct as typically found in the wild, and that these organisms have more than one chromosome.) (a) All gametes formed during a single meiosis will be identical. (b) Due to the random assortment of homologs, each of the gametes formed during a single meiosis will be different. (c) This organism could potentially produce 2n genetically distinct gametes, where n is its haploid number of chromosomes. (d) The fusion of any two gametes produced by such an organism that does not undergo recombination during meiosis will create a cell that is genetically identical to that individual.

Tight junctions ______________________. (a) allow small, water-soluble molecules to pass from cell to cell. (b) interact with the intermediate filaments inside the cell. (c) are formed from claudins and occludins. (d) are found in cells in connective tissues.

Which of the following statements about gap junctions is false? (a) Gap junctions are made of connexons. (b) Molecules up to 1000 daltons in molecular mass can move across gap junctions. (c) Because gap junctions do not allow ions to pass through, they are not used for electrically coupling cells. (d) Gap junctions can close in response to extracellular signals.

Transdifferentiation: 1. The change of a cell or tissue from one differentiated state to another. 2. The differentiation of an already differentiated cell into another type of cell as, for example, a bone cell differentiating into a neuron. Which of the following is TRUE? a) Transdifferentiation requires embryonic stem cells. b) Totipotent stem cells transdifferentiate. c) Transdifferentiation requires changes in gene expression. d) Transdifferentiation likely occurs independent of morphogens. e) Mitochondrial ATPases regenerate irreversibly by processing stem cell lineages uncoupled from the extracellular matrix, thereby leading to synthesis, and most likely initiation, of carcinoma.

Unlike soluble, cytosolic proteins, membrane proteins are more difficult to purify. Which of the following substances is most commonly used to help purify a membrane protein? a) high salt solution b) sucrose c) detergent d) ethanol e) hydrochloric acid

Virus particles placed in a nutrient broth will not replicate unless which of the following is present? A phospholipids for membrane synthesis B reverse transcriptase C living host cells D plasmids

What bacterial group carries out photosynthesis? a) Spirochaetes b) Euryarchaeota c) Cyanobacteria d) Chlamydiae

What is a major similarity between bacteria and archaea? a) They can grow in temperatures above 100°C. b) They form lipid membranes using Ester linkages. c) They contain circular chromosomes. d) They are pathogens.

Which is NOT a protein? a) actin b) ras c) cAMP d) syntaxin e) adenylate cyclase

Which is characteristic of most tumor cells? a) Cannot proliferate in the absence of growth factors. b) Rapid apoptosis. c) An ability to replicate beyond normal limits. d) Mutations in genes encoding VEGF e) An increase in cell adhesion and/or decrease in motility

Which of the following cells is likely be proliferating most rapidly? a) A cell with lots of CDK but no cyclin. b) A cell wherein CDK is not phosphorylated. c) A cell in which phosphorylated CDK is associated with cyclin. d) A cell in which mitochondria are releasing cytochrome C into the cytoplasm. e) A cell in which APC activity is suppressed.

Which of the following descriptions is consistent with the behavior of a cell that lacks a protein required for a checkpoint mechanism that operates in G2? (a) The cell would be unable to enter M phase. (b) The cell would be unable to enter G2. (c) The cell would enter M phase under conditions when normal cells would not. (d) The cell would pass through M phase more slowly than normal cells

Which of the following does not describe a situation of asexual reproduction? (a) A bacterium multiplying by simple cell division. (b) Using a part of a plant to create a new independent plant. (c) Using in vitro fertilization to combine a sperm and an egg to create an embryo. (d) The parthenogenetic development of eggs produced by some species of lizards.

Which of the following is NOT something that directly involves ARP2/3? a) Nucleation of filamentous actin formation b) Extension of lamellipodia c) Beating of cilia d) All of the above - ARP2/3 is involved in a, b, AND c e) None of the above - ARP2/3 is not involved in a, b, or c

Which of the following is a product of glycolysis? a) NADPH b) H2O c) NADH d) FADH2

Which of the following is not a protein? a) adenylate cyclase b) PKA c) cAMP d) IP3 receptor e) PLC

Which of the following molecules is not found in plants? (a) cellulose (b) lignin (c) collagen (d) pectin

Which of the following properties can be expected in a transmembrane protein? A Large amount of hydrophilic residues B Mostly beta-sheet structures C Large amount of hydrophobic residues D A disproportionate amount of histidine

Which of the following protein will be expressed by tumor suppressor p53? (a) Bcl2 (b) Bad (c) p21 (d) E2F

Which of the following statements about cancer is false? (a) Viruses cause some cancers. (b) Tobacco use is responsible for more than 20% of all cancer deaths. (c) A mutation in even a single cancer-critical gene is sufficient to convert a normal cell into a cancer cell. (d) Chemical carcinogens cause cancer by changing the nucleotide sequence of DNA.

ATP... a) is an important source of phosphate for kinases. b) is primarily generated in the mitochondrial matrix. c) is synthesized by 'F0-F1 ATPase' in a reaction that couples transmembrane proton flow to ADP phosphorylation. d) all of the above e) none of the above

Which of the following statements about the EGF and LCGF treatments is LEAST likely? a) Some cell types have receptors for more than one growth factor b) Hepatoma cells have an LCGF receptor but not an EGF receptor c) EGF and LCGF trigger growth by binding with different affinities to the same receptor d) Growth factors show some specificity regarding target cell type e) Both normal and tumor cells can respond to growth factors

Which of the following statements about the anaphase-promoting complex (APC) is false? (a) It promotes the degradation of proteins that regulate M phase. (b) It inhibits M-Cdk activity. (c) It is continuously active throughout the cell cycle. (d) M-Cdk stimulates its activity

Which of the following statements about the round-seeded pea plants obtained in the F2 generation is false? (See Figure Q19-38.) (a) These plants are phenotypically identical for seed shape. (b) Two-thirds of these plants are expected to be heterozygous for the seed-shape allele. (c) We expect 25% of these plants to be homozygous for the seed-shape allele. (d) If these plants were crossed to wrinkle-seeded plants, some of these plants would produce only round-seeded plants.

Which of the following statements is false? (a) Proteoglycans can act as filters to regulate which molecules pass through the extracellular medium. (b) The negative charge associated with proteoglycans attracts cations, which cause water to be sucked into the extracellular matrix. (c) Proteoglycans are a major component of compact connective tissues but are relatively unimportant in watery tissues such as the jellylike substance in the interior of the eye. (d) Glycosaminoglycans are components of proteoglycan

Which of the following statements is true? a) Calcium and diacylglycerol in combination activate adenylate cyclase. b) Many enzyme-coupled receptors (such as receptor tyrosine kinases) have intracellular protein domains that interact with heterotrimeric G-proteins. c) In all eukaryotic cells, transport vesicles continually bud from the trans golgi network and fuse with the plasma membrane, a process called 'constitutive exocytosis'. d) Ribosomes in the cytosol are directed to the ER because the protein they are making has an ER signal sequence, which is recognized by a signal recognition particle inside the lumen of the ER. e) All of the statements above are true.

Which of the following statements is true? a) Large hydrophilic extracellular signal molecules such as steroid hormones and nitric oxide cannot diffuse directly across the plasma membrane. Thus, they bind to intracellular receptors, which usually act as transcription regulators or enzymes when activated. b) There are three main classes of cell-surface receptors: 1) adenylate cyclase, 2) phospholipase C, and 3) nitic oxide synthase. c) GPCRs activate a class of trimeric GTP-binding proteins called G proteins; these act as molecular switches, transmitting the signal onward for a short period and then switching themselves off by hydrolyzing GTP to GDP. d) IP3 opens calcium channels in the membrane of the endoplasmic reticulum, allowing calcium ions to flow from the cytosol into the ER. e) Protein kinase A is responsible for the synthesis of cAMP.

Which of the following things is TRUE about the plus (+) end of microtubules? a) They are slower growing, compared to the minus (-) end b) Dynein goes toward them c) They tend to be associated with GTP d) They tend to be associated with centrosomes e) They do not contain tubulin

Which of the following types of mutations would most likely lead to cancer? a) A mutation that makes a chemokine receptor nonfunctional b) A mutation that makes the GTPase RAS inactive c) A mutation that reduces expression of p53 d) A mutation that leads to overexpression of caspases e) A mutation in increases expression of Rb protein

Which of these is false? a) Apoptosis is responsible for separation of fingers and toes during development. b) Necrosis typically responds to negative environmental factors. c) Blebbing is characteristic of necrosis. d) Degradation of tadpole tail is due to apoptosis. e) A cell tends to burst and release its contents as a result of necrosis.

Which protein can you most thank for the fact that you are not covered with open sores? a) PKC b) Tau c) Keratin d) Connexin e) Calmodulin

Which type of junction contributes the most to the polarization of epithelial cells? (a) adherens junctions (b) desmosomes (c) tight junctions (d) gap junctions

Which type of the following cancers is the most common type of cancer? a. Leukemia b. Sarcoma c. Carcinoma d. melanoma

Wil dispose of dying cells in the mamalian skin ? A. fibroblast B. Schwann cells C. macrophage d. blood vessels e. lymphocytes

Wnt signal transduction pathway is critical for multiple cellular events . What is the role of Wnt athway in stem cell function in intestinal cillus and crypt? a. cell stem cell differentiation into secretory cells b.cell stem cell differentiation into absorptive cells c. cel stem cell proliferation d. apoptosis of terminally differentiated cells

You engineer yeast cells that express the M cyclin during S phase by replacing the promoter sequence of the M cyclin gene with that of S cyclin. Keeping in mind that yeast cells have one common Cdk that binds to all cyclins, which of the following outcomes is least likely during this experiment? (a) There will be both M cyclin-Cdk and S cyclin-Cdk complexes in the cell during S phase. (b) Some substrates that are normally phosphorylated in M phase will now be phosphorylated in S phase. (c) G1 cyclins will be expressed during S phase. (d) S-Cdk targets will be phosphorylated during S phase.

You examine a worm that has two genders: males that produce sperm and hermaphrodites that produce both sperm and eggs. The diploid adult has four homologous pairs of chromosomes that undergo very little recombination. Given a choice, the hermaphrodites prefer to mate with males, but just to annoy the worm, you pluck a hermaphrodite out of the wild and fertilize its eggs with its own sperm. Assuming that all the resulting offspring are viable, what fraction do you expect to be genetically identical to the parent worm? Assume that each chromosome in the original hermaphrodite is genetically distinct from its homolog. (a) all (b) none (c) 1/16 (d) 1/256

Your friend is studying mouse fur color and has isolated the GPCR responsible for determining its color, as well as the extracellular signal that activates the receptor. She finds that, on addition of the signal to pigment cells (cells that produce the pigment determining fur color), cAMP levels rise in the cell. She starts a biotech company, and the company isolates more components of the signaling pathway responsible for fur color. Using transgenic mouse technology, the company genetically engineers mice that are defective in various proteins involved in determining fur color. The company obtains the following results. Normal mice have beige (very light brown) fur color. Mice lacking the extracellular signal have white fur. Mice lacking the GPCR have white fur. Mice lacking cAMP phosphodiesterase have dark brown fur. Your friend has also made mice that are defective in the α subunit of the G protein in this signaling pathway. The defective α subunit works normally except that, once it binds GTP, it cannot hydrolyze GTP to GDP. What color do you predict that the fur of these mice will be? a) very light brown b) white c) dark brown d) black

_____ belongs to a group of molecules called mitogen, stimulates cell division by releasing the molecular brakes that keep cells in the G0 or G1 phase of the cell cycle. (a) Nitric Oxide (b) Adrenalin (c) EGF (d) growth hormone

_______ is called a member of growth factors because it stimulates cell growth and an increase in cell mass. (a) Src (b) p53 (c) PDGF (d) LKB1

________ are primarily used for attachment, and employ the use of molecules called ______ to attach to extracellular surfaces or host cells, whereas __________ are mainly used for movement. a) Flagella; Pilin; Pili b) Flagella; Adhesin; Pili c) Pili; Adhesin; Flagella d) Pili; Pilin; Flagella

__________ are fairly small organelles that provide a safe place within the cell to carry out certain biochemical reactions that generate harmful, highly reactive oxygen species. These chemicals are both generated and broken down in the same location. (a) Nucleosomes (b) Lysosomes (c) Peroxisomes (d) Endosomes

__________ are fairly small organelles that provide a safe place within the cell to carry out certain biochemical reactions that generate harmful, highly reactive oxygen species. These chemicals are both generated and broken down in the same location. a) nucleosomes b) lysosomes c) peroxisomes d) endosomes e) ribosomes

"Androgel" is testosterone dissolved in a gel. It is rubbed onto the skin as 'testosterone replacement therapy' to treat low testosterone, most often in males. Which of the following is TRUE? a) Testosterone cannot penetrate membranes, and therefore is unlikely to penetrate the skin. b) Testosterone binds to G-protein coupled receptors. c) Androgel is a testosterone receptor antagonist. d) Testosterone receptor antagonists would block the effect of Androgel. e) Androgel is a receptor in the cytoplasm, which travels to the nucleus when testosterone binds.

) All of the following statements apply to microtubules EXCEPT: a) They are able to move vesicles and other storage inclusions b) They serve a cytoskeletal role c) They are linear polymers of tubulin d) They make up the thin myofilament in skeletal muscle

1. Many features of _____ cells make them suitable for biochemical studies of the cell-cycle control system. For example, the cells are unusually large and are arrested in a G2-like phase. (a) fibroblast (b) neuronal (c) epithelial (d) egg

Actin filaments and microtubules share all of the following properties EXCEPT: a) They are involve din cell motility b) They are intrinsically polar structures c) They can associate with motor proteins d) They are assembled from subunits that are heterodimers e) They can be cross-linked into bundles

50) Which two things are about the same size? a) A mitochondrion and a virus b) A bacteria and a virus c) A red blood cell and a bacterium d) A bacterium and a chloroplast e) A ribosome and a bacterium

A benign umore is less dangerous than a malignant tumor because a. its cell are proliferating slower b. its cells don't cause neighboring cells to mutate c. its cells attack and phagocytose neighboring tumor cells d. its cells dont migrate and colonize other tissues

A crazy (but brilliant!) scientist wants to clone himself from stem cells and build an army of mad warriors, but is unable to obtain the human stem cells he needs for his plan. Luckily he remembers that plants also have stem cells, and decides to clone himself from plant stem cells. Do you think his plan will work? a) Sure, it might work. A stem cell is a stem cell, and by definition a stem cell can differentiate into any other type of cell. b) Yes, for the reason given in answer a, but ONLY if differentiation of the plant stem cell occurs in the presence of human cells that are needed to provide appropriate cell growth signals (for example, the proper signal that occurs when skin cells separate from the basal lamina). c) The plan will never work because plants do not really have stem cells. d) The plan will not work because plant stem cells can only differentiate into plant cells (in part because the genomes are different between humans and plants). e) The scientist will be able to clone himself fine from the plant cells, but he will not be able to produce more than one clone because the telomeres will get too short.

A malignant tumor is more dangerous than a benign tumor because ______________________. (a) its cells are proliferating faster. (b) it causes neighboring cells to mutate. (c) its cells attack and phagocytose neighboring normal tissue cells. (d) its cells invade other tissues.

A single nondisjunction event during meiosis ___________________. (a) will block recombination. (b) will occur only during meiosis II. (c) cannot occur with sex chromosomes. (d) will involve the production of two normal gametes if it occurs during meiosis II.

Adenoma is less dangerous than Adenocarcinoma because ________________. (a) its cells are proliferating slower (b) its cells don't cause neighboring cells to mutate (c) its cells attack and phagocytose neighboring tumor cells (d) its cells don't migrate and colonize other tissues

After isolating the rough endoplasmic reticulum from the rest of the cytoplasm, you purify the RNAs attached to it. Which of the following proteins do you expect the RNA from the rough endoplasmic reticulum to encode? (a) soluble secreted proteins (b) ER membrane proteins (c) plasma membrane proteins (d) all of the above

All are components of eukaryotic cell membranes, except: A Glycolipid B Cholesterol C Phospholipid D Peptidoglycan

All of the following statements apply to microtubules EXCEPT: a) They are able to move vesicles and other storage inclusions b) They serve a cytoskeletal role c) They are linear polymers of tubulin d) They make up the thin myofilament in skeletal muscle

Both multicellular plants and animals have _____________________. (a) cells capable of locomotion. (b) cells with cell walls. (c) a cytoskeleton composed of actin filaments, microtubules, and intermediate filaments. (d) tissues composed of multiple different cell types.

By weight, which of the following is generally MOST abundant in cell membranes? a) Phospholipids b) Glycolipids c) Cholesterol d) Protein e) Triacylglycerides

CELL BIOS does not refer to just human cells.... most cells in the human body aren't actually human! Over 90% are bacterial cells! What purpose, if any, do these bacterial cells serve? a) They prevent us from getting sick and missing BIOS 222 lecture (our normal flora bacteria help prevent other harmful bacteria from colonizing our bodies). b) They allow some of us to eat sushi (they aid in the digestion of certain foods, for example Japanese decedents can digest the cellulose in nori). c) They help make us drunk (bacteria in our mitochondria anaerobically catabolize alcohol into acetic acid (vinegar) inside our cells. The acetic acid builds up in our cells and makes us feel drunk and too hungover to go to our final on Monday). d) Choice a and b are correct. e) All of the above.

Calcium released from the sarcoplasmic reticulum will diffuse and bind to which protein? a) F-actin b) myosin c) tropomyosin d) troponin C

Cancer cells tend to be particularly good at... a) proliferation, apoptosis, basal lamina secretion, and angiogenesis b) proliferation, DNA repair, and basal lamina breakdown c) cell adhesion and inhibition of mitosis d) degrading extracellular matrix and avoiding immune system recognition e) initiating promosis

Caspases are... a) proteases activated by APC to degrade cyclin. b) proteins that suppress apoptosis. c) protein kinases. d) activated during apoptosis. e) Proteins that degrade the extracellular matrix to promote metastasis.

Cell proliferation during development is typically regulated by growth factor receptors. Which of the following is a type of growth factor receptor? a) The myostatin receptor b) The her2 receptor c) The EGF receptor d) All of the above e) None of the above

Cellular proteins destined for secretion are sorted and packaged in the a) lysosomes b) endosomes c) endoplasmic reticulum d) trans golgi network e) peroxisomes

Cholesterol is a compound within membranes which acts to increase fluidity under low temperatures and decrease fluidity during high temperatures. If the membrane is composed of phospholipids with higher melting points, the membrane will be less fluid. Which of the following may act to increase the fluidity of a membrane? a) Increasing cholesterol concentration in the membrane b) Increasing intracellular calcium concentrations c) Increasing the average length of the phospholipids d) Increasing desaturation within the membrane

Cholesterol is a compound within membranes which acts to increase fluidity under low temperatures and decrease fluidity during high temperatures. If the membrane is composed of phospholipids with higher melting points, the membrane will be less fluid. Which of the following may act to increase the fluidity of a membrane? A Increasing cholesterol concentration in the membrane B Increasing intracellular calcium concentrations C Increasing the average length of the phospholipids D Increasing desaturation within the membrane

Diabetes is a disease caused by a lack of insulin or ability of cells to respond to insulin. Insulin is a hormone that causes cells to put GLUT4 proteins into the plasma membrane. GLUT4, whose full name is 'Glucose transporter type 4', allows facilitated diffusion of glucose into cells. Based on this information, which of the following is TRUE? a) The concentration of glucose is typically higher outside cells compared to inside the cell cytoplasm. b) Glucose transport via GLUT4 does not require the break down of ATP into ADP. c) GLUT4 is a transmembrane protein. d) All of the above is true. e) None of the above is true.

Disassembly of the nuclear envelope ________________. (a) causes the inner nuclear membrane to separate from the outer nuclear membrane (b) results in the conversion of the nuclear envelope into protein-free membrane micelles (c) is triggered by the phosphorylation of integrins (d) must occur for kinetochore microtubules to form in animal cells

Disassembly of the nuclear envelope ________________. (a) causes the inner nuclear membrane to separate from the outer nuclear membrane. (b) results in the conversion of the nuclear envelope into protein-free membrane vesicles. (c) is triggered by the phosphorylation of integrins. (d) must occur for kinetochore microtubules to form in animal cells.

Loss-of-function mutations ________________________. (a) cause the production of proteins that are active in inappropriate circumstances. (b) will usually show a phenotype when heterozygous. (c) are only present in a population at barely detectable levels. (d) are usually recessive.

During sexual reproduction, novel mixtures of alleles are generated. This is because ______. (a) in all diploid species, two alleles exist for every gene. (b) a diploid individual has two different alleles for every gene. (c) every gamete produced by a diploid individual has several different alleles of a single gene. (d) during meiosis, the segregation of homologs is random such that different gametes end up with different alleles of each gene.

During strenuous (anaerobic) exercise, you may notice that your muscles 'burn'. Which of the following best explains this phenomenon. a) Proteins are being digested to provide energy. b) Carbon dioxide buildup in muscle is changing the pH to be more acidic. c) Protons (which lower the pH) are accumulating in the cytoplasm after flowing through ATP synthase. d) Pyruvate is being converted to lactic acid. e) Glycolysis is being bypassed in favor of oxidative phosphorylation.

Dyneins... a) are actin-regulating proteins b) are non-motor MAPs c) are part of the nuclear lamina d) are ATPases e) are found only in vertebrates

Fibroblasts organize the collagen of the extracellular matrix by ______________. (a) cutting and rejoining the fibrils. (b) processing procollagen into collagen. (c) twisting fibrils together to make ropelike fibers. (d) pulling the collagen into sheets or cables after it has been secreted.

From 'Milestones: Cytoskeleton' (Katherine Whalley, Nature, Dec 1 2008): "In the 1950s, the blossoming field of electron microscopy had allowed the structure of the axoneme — the structural core of cilia and flagella — to be visualized, revealing the now familiar arrangement of nine microtubule doublets, linked by protein 'arms', surrounding a central microtubule pair. However, little was known about the protein components of the axoneme. Axoneme-isolation studies had demonstrated that axoneme motility required an ATPase. In 1965, Gibbons and Rowe identified an ATPase with enzymatic and structural properties matching those of the axoneme arms within the ciliated protozoon Tetrahymena pyriformis." What did Gibbons and Rowe name the ATPase that they discovered? a) F0-F1 b) The axoneme c) Tubulin d) Dynein e) Nexin

Hemidesmosomes are important for ______________________. (a) tubulation of epithelial sheets. (b) linkages to glycosaminoglycans. (c) forming the basal lamina. (d) attaching epithelial cells to the extracellular matrix

How do reproductive cloning and therapeutic cloning differ? (a) The DNA in the nucleus of cells produced for therapeutic cloning is genetically identical to the donor genome, whereas in cells produced for reproductive cloning it is not. (b) Reproductive cloning requires a supply of fertilized donor egg cells, whereas therapeutic cloning requires unfertilized egg cells. (c) Therapeutic cloning requires nuclear transplantation, whereas reproductive cloning does not. (d) Embryos are placed into foster mothers during reproductive cloning but not during therapeutic cloning.

I am a small, typically round granular body composed of protein and RNA. I am usually associated with a specific chromosomal site and involved in ribosomal RNA synthesis and the formation of ribosomes. What am I? a) The cytosol b) A lysosomes c) The nucleus d) A nucleolus e) A ribosome

If a muscle cell is poked with a needle calcium will...? a) Move out of the cell. b) Do nothing. c) Move away from the poked cell. d) Move into the cell and attach to troponin. e) Both C and D.

Imagine meiosis in a diploid organism that only has a single chromosome. Like most diploid organisms, it received one copy of this chromosome from each of its parents and the two homologs are genetically distinct. If only a single homologous recombination event occurs during meiosis, which of the following choices below correctly describes the four gametes formed. (a) None of the gametes will contain chromosomes identical to the chromosomes found in the original diploid cell. (b) All four of the gametes will have chromosomes identical to the chromosomes found in the original diploid cell. (c) Three of the gametes will have chromosomes identical to the chromosomes found in the original diploid cell, while one of the gametes will have chromosomes that are different. (d) Two of the gametes will have chromosomes identical to the chromosomes found in the original diploid cell, while two of the gametes will have chromosomes that are different.

In addition to stimulatory factors, some signal proteins such as ________ act negatively on other cells, inhibiting their survival, growth, or proliferation. (a) Adrenalin (b)Wnt (c) EGF (d) myostatin

In respiration, oxygen... a) combines with lactic acid to form pyruvic acid b) acts as a cofactor for glycolytic enzymes c) yields energy in the form of ATP as it is passed down the respiratory chain d) acts as an acceptor for electrons (and protons), forming water e) combines directly with carbon, forming CO2

Levels of Cdk activity change during the cell cycle, in part because ________________. (a) the Cdks phosphorylate each other. (b) the Cdks activate the cyclins. (c) Cdk degradation precedes entry into the next phase of the cell cycle. (d) cyclin levels change during the cycle.

Look at the diagram on the right. What is the structure in the lower right, labeled with the asterisk * ? a) The nucleus b) The endoplasmic reticulum c) A periplasmic space d) A vacuole e) A mitochondrion

MPF activity was discovered when cytoplasm from a Xenopus M-phase cell was injected into Xenopus oocytes, inducing the oocytes to form a mitotic spindle. In a control experiment, Xenopus interphase cytoplasm was injected into oocytes and shown not to induce the formation of a mitotic spindle. Which of the following statements is not a legitimate conclusion from the control experiment?

MPF activity was found to be oscillate during the cell cycle, although the amount of its kinase component, called _______, remained constant. (a) Src (b) MAPK (c) GSK3 (d) Cdk

Malignant tumor development is more common in the elderly because: a) It takes time to acquire mutations that cause malignant tumors b) The immune system in the elderly is weaker than the immune system of younger individuals c) The medication of elderly individuals puts them at a high risk for developing malignant tumors d) A and B e) All of the above

Mouse embryonic stem (ES) cells ______________________. (a) can only be produced through therapeutic cloning. (b) can give rise to all tissues and cell types in the body except germ cells. (c) can be implanted in foster mothers to produce cloned cows and other animals. (d) come from the inner cell mass of early embryos.

Naloxone is a drug given to individuals who present in the emergency room suspected of opiate overdose (such as heroin). Naloxone acts on opiate receptors to block the binding of the opiates in the body, thus negating their toxic effects. The drug acts quite quickly such that patients will suddenly wake up from unconsciousness upon administration. Naloxone has a half-life of around 30 minutes (as compared with 4 hours for many opiates). As such, the patient may revert into the unconscious state when the naloxone effects have worn off and the opiates continue to have their effects. Which of the following types of inhibition is POSSIBLE of the naloxone-opiate receptor system? I. Noncompetitive inhibitor II. Competitive inhibitor III. Nonreversible Inhibitor a) I only b) II only c) II and III only d) I, II, and III

Now imagine that the tumor (described in the previous question) is removed, and the tumor cells are studied in detail. Which of the following things do you think is most likely to be TRUE? a) The tumor cells show increased cyclin/CDK activity b) The tumor cells have mutations that suppress cyochrome C release from mitochondria c) Microtubules in the tumors cells are able to form mitotic spindles d) All of the above is likely to be true e) None of the above is likely to be true

Of which the onogenic activations mutation will facilitate colon cancer progress? a apc b. p53 c.Rb d. Ras

Organisms that reproduce sexually ________________________. (a) must be haploid, unlike organisms that reproduce asexually. (b) can reproduce only with a partner that carries the same alleles. (c) create zygotes that are genetically identical to each other. (d) undergo a sexual reproductive cycle that involves an alternation of haploid cells with the generation of diploid cells.

Plant cell walls... a) are composed primarily of collagen and elastin b) are digested primarily in the stomach, which is probably why cows have more stomachs than humans c) are incorrectly assembled in Ehlers-Danlos syndrome d) are a type of extracellular matrix e) are an example of a type of adhesion plaque

Proteins that are fully translated in the cytosol do not end up in _______. (a) the cytosol. (b) the mitochondria. (c) the interior of the nucleus. (d) transport vesicles.

Red blood cells have been very useful in the study of membranes and the protein components that provide structural support. Which of the following proteins is the principal fibrous protein in the cortex of the red blood cell? (a) tubulin (b) attachment proteins (c) actin (d) spectrin

Studies with Xenopus eggs identified a partly purified activity called _____ that drives a resting Xenopus oocyte into M phase. A. cyclin b. Src c.Cdk D. MPF

The G1 DNA damage checkpoint ________________. (a) causes cells to proceed through S phase more quickly. (b) involves the degradation of p53. (c) is activated by errors caused during DNA replication. (d) involves the inhibition of cyclin-Cdk complexes by p21.

The G2 checkpoint ___ a. cause cells to proceed through S phase more quickly b. involves the degradation of p53 c. activated by errors caused during DNA replication d. must occur for kinetochore microtubles in form in animal cell

The Wartburg effect suggests that... a) tumor cells cannot perform fermentation b) stem cells consume more oxygen than other types of cells c) tumor cells contain higher-than-normal numbers of mitochondria d) rapidly proliferating cells produce more lactic acid than cells in cell cycle arrest e) tumor cells do not require ATP

The __________ __________ is made up of two concentric membranes and is continuous with the membrane of the endoplasmic reticulum. (a) plasma membrane (b) Golgi network (c) mitochondrial membrane (d) nuclear envelope

The extrinsic apoptotic pathway will be initiated by the binding of the Fas ligand presented on the cytotoxic T lymphocyte. Upon the death ligand binding to death receptor, initiator caspases will be activated that will in turn activate _____. (a) Bcl2 (b) Cytochrome c (c) p53 (d) excusioner caspase

The introduction of continuous nocturnal glucose feeds and uncooked cornstarch has improved the prognosis for patients with hepatic glycogen storage diseases. In these patients, where does glucose get converted into pyruvate? a) nucleus b) mitochondria c) smooth endoplasmic reticulum d) cytosol

The length of time a G protein will signal is determined by _______. (a) the activity of phosphatases that turn off G proteins by dephosphorylating Gα. (b) the activity of phosphatases that turn GTP into GDP. (c) the degradation of the G protein after Gαseparates from Gβγ (d) the GTPase activity of Gα

The picture shows blood vessels growing toward a tumor (in the dark area of the photo, center left). This is an example of: a) The ability of tumors to increase angiogenesis b) The effect of a growth factor c) cell proliferation and differentiation d) all of the above e) none of the above

Think about a cell, and the watery cytoplasm inside it. About how much space inside a cell is relatively empty fluid? a) Almost all of it b) A lot, maybe 50% or more c) A small amount, maybe 10-20% d) Almost none; cells are jam-packed with stuff e) Cells do not contain much water

Tissues are organized mixtures of many cell types with certain basic requirements. Which of the following is not one of them? (a) Mechanical strength (b) Blood supply (c) Nerve (d) apoptotic machinery

What is "vascular endothelial growth factor"? a) A protein often produced by tumors b) A secreted substance that promotes blood vessel growth c) Something that is inhibited by 'avastin.' d) All of the above. e) None of the above.

What is a 'morphogen'? a) an example of a cell fate b) a type of cell lineage c) a type of stem cell d) something that causes changes in gene expression e) an induced pluripotency

What is the role of oxygen in respiration? a) Oxygen is combined with carbon from the foods you eat after those foods are broken down to provide energy. b) Oxygen is combined with pyruvate to generate CO2 in the TCA cycle. c) Oxygen acts as a final carbon acceptor in each 'turn' of the TCA cycle. d) Electrons passing through the electron transport chain during oxidative phosphorylation are eventually combined with protons and oxygen to form water. e) Hydrogen ions are carried from the mitochondrial matrix membrane by the oxygen, which can pass through membranes because it is a gas

What unit of length would you generally use to measure a typical human cell? a) centimeters b) nanometers c) millimeters d) micrometers e) microscope

What unit of length would you generally use to measure a typical plant or animal cell? (a) centimeters (b) nanometers (c) millimeters (d) micrometers

When introduced into mitotic cells, which of the following is expected to impair anaphase B but not anaphase A? (a) an antibody against myosin (b) ATPγS, a nonhydrolyzable ATP analog that binds to and inhibits ATPases (c) an antibody against the motor proteins that move from the plus end of microtubules to the minus end (d) an antibody against the motor proteins that move from the minus end of microtubules toward the plus end

Where are stem cells found? a) Bone marrow b) epidermis (skin) c) Adult humans d) All of the above e) None of the above

Which is NOT characteristic of most malignant tumor cells? a) An ability to proliferate in the absence of growth factors. b) Inhibition of apoptosis. c) An ability to replicate beyond normal limits. d) Suppression of angiogenesis e) A decrease in cell adhesion and/or increase in motility

Which is the smallest organelle in the cell? A) Golgi body B) Nucleus C) Mitochondrion D) Ribosome E) Chloroplast

Which of the following canonical signaling cascades is NOT correctly described? a) Phospholipase C (PLC) cleaves PIP2 into IP3 and DAG; DAG then activates protein kinase C. b) RAS activates RAF, which phosphorylates a MAP kinase kinase, which phosphorylates a MAP kinase, which phosphorylates a transcription factor. c) IP3 triggers opening of IP3 receptors in the endoplasmic reticulum, allowing calcium to move from the ER to the cytoplasm. d) A GTPase-activating protein (GAP) turns on RAS by triggering release of GDP and binding of GTP. e) Mechanical pressure on the extracellular portion of a mechanoreceptor causes opening of an ion channel portion of the receptor, allowing calcium into the cytoplasm.

Which of the following does NOT normally occur in healthy developing tissue? a) Differentiation b) Angiogenesis c) Apoptosis d) All of the above normally occur in healthy developing tissue. e) None of the above normally occur in healthy developing tissue.

Which of the following is MOST likely to be involved with initiation and/or progression of cancer? a) An increase in G-protein GTPase activity downstream of a growth factor receptor b) Mutations in the gene encoding P53 protein c) Mutations in the promoter of the Rb gene, causing overexpression of Rb d) Mutations that increase growth factor receptor expression e) Mutations that inactivate proteases capable of breaking down the basal lamina

Which of the following is NOT a characteristic of intermediate filaments? a) They form the nuclear lamina. b) They provide mechanical stability to animal cells. c) Their protein composition is tissue specific. d) They are composed of globular monomers that polymerize to form fibers. e) They include keratin filaments of epithelial cells.

Which of the following is NOT a transmembrane protein? a) Cadherin b) Integrin c) Connexin d) Lamin e) ALL of the above are transmembrane proteins

Which of the following is NOT a transmembrane protein? a) Cadherin b) Integrin c) Connexin d) Laminin e) ALL of the above are transmembrane proteins

Which of the following is NOT correctly described? a) Phospholipase C (PLC) cleaves PIP2 into IP3 and DAG; DAG then activates protein kinase C. b) RAS activates RAF, which phosphorylates a MAP kinase kinase, which phosphorylates a MAP kinase, which phosphorylates a transcription factor. c) IP3 triggers opening of IP3 receptors in the endoplasmic reticulum, allowing calcium to move from the ER to the cytoplasm. d) Mitotic cyclin binds to mitotic CDK, inhibiting APC and causing cell cycle arrest. e) Absence of trophic factors triggers release of cytochrome C from mitochondria, activation of caspases,and subsequent apoptosis.

Which of the following is NOT normally considered an organelle? a) Nucleus b) Endoplasmic reticulum c) Mitochondria d) Cytoskeleton e) Lysosome

Which of the following is NOT something that directly involves ARP2/3? a) Nucleation of filamentous actin formation b) Extension of lamellipodia c) Listeria bacteria propulsion d) All of the above - ARP2/3 is involved in a, b, AND c e) None of the above - ARP2/3 is not involved in a, b, or c

Which of the following is TRUE about angiogenesis? a) It leads to necrotic cell death. b) It leads to p53 activation and subsequent cell 'suicide'. c) It is inhibited by VEGF. d) It is typically increased in malignant tumors. e) It is caused by release of avastin from epithelial cells.

Which of the following is TRUE about sperm? a) Sperm tail movement is driven primarily by actin filament reorganization. b) Sperm cells are prokaryotic. c) It takes a lot of ATP to make a sperm tail wiggle for hours. This ATP is synthesized, like other proteins, by ribosomes. d) The concentration of calcium in the cytoplasm of sperm cells is very low compared to the concentration of calcium inside the endoplasmic reticulum. e) A drug that blocks kinesin activity would probably have no effect on the number of receptors in the plasma membrane of sperm cells.

Which of the following is an example of cell differentiation? a) Apoptosis b) Binding of a chemokine to a receptor tyrosine kinase c) Phosphorylation of Rb protein d) Increased expression of matrix metalloproteases by tumor cells e) Sloughing (shedding) of keratinized skin cells

Which of the following is not good direct evidence that the cell-cycle control system is conserved through billions of years of divergent evolution? (a) A yeast cell lacking a Cdk function can use the human Cdk to substitute for its missing Cdk during the cell cycle. (b) The amino acid sequences of cyclins in plants are similar to the amino acid sequences of cyclins in humans. (c) The Cdk proteins in humans share conserved phosphorylation sites with the Cdk proteins in yeast. (d) Yeast cells have only one Cdk, whereas humans have many Cdks.

Which of the following is the most accurate description of intercellular (cell to cell) chemical signaling? a) A signal molecule binds to a receptor in the plasma membrane, triggering activation of G-proteins that activate other proteins by phosphorylation. These phosphorylated proteins cause a cellular response b) A signal molecule binds to a receptor, which is by definition any sort of protein that binds the signal molecule. After this receptor binds the signaling molecule (also called a 'ligand'), the receptor converts to an adenylate cyclase and generates CaM kinase, which phsophorylates other proteins, eventually leading to a cellular response c) A signal molecule, typically named Bob, wanders down the street until it bumps into a lamppost and falls over. Somewhere, a dog howls. d) A signal molecule binds to a receptor, which can be inside the cell or embedded in the plasma membrane, causing activation of this receptor. Receptor activation then triggers a 'signaling cascade', in which a series of enzymes (such as CaM kinase, protein kinase, and adenylate cyclase) catalyze the formation of other signaling molecules that eventually activate a cellular response. e) Signaling molecules can be released from nearby cells ('endocrine signaling'), transported from cells far away (paracrine signaling), or the target cell itself ('autocrine signaling'). In each case, the signaling molecule binds to receptors on or in the target cell to cause either a change in intracellular ion concentration (i.e. an increase in intracellular calcium) or activation of intracellular G-proteins or enzymes like kinases. G-proteins and kinases in turn activate other proteins and/or generate 'second messengers', which eventually leads to a cellular response

Which of the following membrane lipids does not contain a fatty acid tail? (a) Phosphatidylcholine (b) A glycolipid (c) Phosphatidylserine (d) Cholesterol

Which of the following membrane lipids does not contain a fatty acid tail? a) Phosphatidylcholine b) A glycolipid c) Phosphatidylserine d) Cholesterol e) Blood type A antigen: The molecule that makes a blood cell 'type A'

Which of the following protein associates with the tumor suppressor Rb? (a) APC (b) p53 (c) Myc (d) E2F

Which of the following proteins is typically associated with actin filaments? a) kinesin b) dynein c) tau d) ARP e) Nexin

Which of the following reasons was essential for Mendel to disprove the theory of blended inheritance? (a) The traits that Mendel examined all involved genes that did not display linkage. (b) The traits that Mendel examined all involved the reproductive structures of the pea plant. (c) Mendel pioneered techniques permitting the fusion of male and female gametes from the same plant to produce a zygote. (d) The traits that Mendel examined involved an allele that was dominant and an allele that was recessive.

Pick the BEST answer: Vesicles and other organelles are transported within cells when... a) Kinesin or dynein attach the organelle to a microtubule and the microtubule grows b) Filopodia push the organelles from place to place c) Myosin 'walks' the organelles along actin d) Dynein arms pull the organelles along axonemes e) Motor MAPs carry the organelles along a microtubule

Which of the following statements about G-protein-coupled receptors (GPCRs) is false? (a) GPCRs are the largest family of cell-surface receptors in humans. (b) GPCRs are used in endocrine, paracrine, and neuronal signaling. (c) GPCRs are found in yeast, mice, and humans. (d) The different classes of GPCR ligands (proteins, amino acid derivatives, or fatty acids) bind to receptors with different numbers of transmembrane domains.

Which of the following statements about Mendel's experiments is false? (a) The pea plants could undergo both cross-fertilization and self-fertilization. (b) The true-breeding strains were homozygous for the traits that Mendel examined. (c) The egg can carry either the allele from the maternal or the paternal chromosome. (d) All traits that Mendel studied were recessive.

Which of the following statements about a protein in the lumen of the ER is false? (a) A protein in the lumen of the ER is synthesized by ribosomes on the ER membrane. (b) Some of the proteins in the lumen of the ER can end up in the extracellular space. (c) Some of the proteins in the lumen of the ER can end up in the lumen of an organelle in the endomembrane system. (d) Some of the proteins in the lumen of the ER can end up in the plasma membrane.

Which of the following statements about animal connective tissues is true? (a) Enzymes embedded in the plasma membrane synthesize the collagen in the extracellular matrix extracellularly. (b) In connective tissue, the intermediate filaments within the cells are important for carrying the mechanical load. (c) Cells can attach to a collagen matrix by using fibronectin, an integral membrane protein. (d) Proteoglycans can resist compression in the extracellular matrix.

Which of the following statements about apoptosis is true? (a) Cells that constitutively express Bcl2 will be more prone to undergo apoptosis. (b) The prodomain of procaspases contains the catalytic activity necessary for procaspase activation. (c) Bax and Bak promote apoptosis by binding to procaspases in the apoptosome. (d) Apoptosis is promoted by the release of cytochrome c into the cytosol from mitochondria.

Which of the following statements about cancer is false? (a) Viruses cause some cancers. (b) Tobacco use is responsible for more than 20% of all cancer deaths. (c)Obesity is often linked with cancer (d) Oncogene cooperation happens only in virus induced cancers

Which of the following statements about cancer is false? (a) Viruses cause some cancers. (b) Tobacco use is responsible for more than 20% of all cancer deaths. (c) Obesity is often linked with cancer. (d) Oncogene cooperation happens only in virus-induced cancers.

Which of the following statements about cellulose is false? (a) Cellulose synthase enzyme complexes are integral membrane proteins. (b) An array of microtubules guides the cellulose synthase complex as it moves in the membrane. (c) The sugar monomers necessary for the synthesis of a cellulose polymer are transported across the plasma membrane. (d) Microtubules are directly attached to the outside surface of the plasma membrane to form tracks that help orient the cellulose polymers.

Which of the following statements about genome-wide association studies (GWAS) is false? (a) GWAS use SNPs to compare populations of people with disease and people without disease to look for SNPs more likely to be present in those with disease. (b) GWAS can be used even if more than one gene can cause the disease of interest. (c) Sometimes GWAS will identify SNPs that are associated with a disease but these SNPs do not affect the gene product of the gene that causes the disease. (d) Studies using GWAS only examine SNPs that occur very rarely (<0.001%) in the population, as those SNPs are most likely to cause disease.

Which of the following statements about the cell cycle is TRUE? a) The activity of cyclin/CDK protein complexes determine whether a cell will progress through the cell cycle. b) Cells which are not activity progressing through the cell cycle are said to be 'arrested'. c) Relatively rapid and uncontrolled progression through the cell cycle leads to hyperplasia. d) All of the above are true. e) None of the above are true.

Which of the following statements is TRUE? a) Cyclin is a kinase b) Cyclin is necessary for cell division c) Sea urchin eggs do not contain CDK proteins d) Fertilization stops synthesis of cyclin e) Cyclins are secreted via SNARE-dependent exocytosis

Which of the following statements is TRUE? a) Necrosis is the first stage of apoptosis. b) Cells typically lyse during apoptosis. c) Apoptosis is triggered by active CDK. d) Caspase activation leads to apoptosis. e) Caspases cause polyubiquitination of cyclin.

Which of the following statements is false? (a) Nucleotides and amino acids can act as extracellular signal molecules. (b) Some signal molecules can bind directly to intracellular proteins that bind DNA and regulate gene transcription. (c) Some signal molecules are transmembrane proteins. (d) Dissolved gases such as nitric oxide (NO) can act as signal molecules, but because they cannot interact with proteins they must act by affecting membrane lipids.

Which of the following statements is false? (a) Cytokinesis in plant cells is mediated by the microtubule cytoskeleton. (b) Small membrane vesicles derived from the Golgi apparatus deliver new cell-wall material for the new wall of the dividing cell. (c) The phragmoplast forms from the remains of interpolar microtubules of the mitotic spindle. (d) Motor proteins walking along the cytoskeleton are important for the contractile ring that guides formation of the new cell wall.

Which of the following statements is false? (a) Mitotic Cdk must be phosphorylated by an activating kinase (Cak) before it is active. (b) Phosphorylation of mitotic Cdk by the inhibitory kinase (Wee1) makes the Cdk inactive, even if it is phosphorylated by the activating kinase. (c) Active M-Cdk phosphorylates the activating phosphatase (Cdc25) in a positive feedback loop. (d) The activating phosphatase (Cdc25) removes all phosphates from mitotic Cdk so that M-Cdk will be active.

Which of the following statements is false? (a) The cleavage furrow is a puckering of the plasma membrane caused by the constriction of a ring of filaments attached to the plasma membrane. (b) The cleavage furrow will not begin to form in the absence of a mitotic spindle. (c) The cleavage furrow always forms perpendicular to the interpolar microtubules. (d) The cleavage furrow always forms in the middle of the cell.

Which of the following statements is true? (a) Anaphase A must be completed before anaphase B can take place. (b) In cells in which anaphase B predominates, the spindle will elongate much less than in cells in which anaphase A dominates. (c) In anaphase A, both kinetochore and interpolar microtubules shorten. (d) In anaphase B, microtubules associated with the cell cortex shorten.

Which of the following statements is true? (a) The mitotic spindle is largely made of intermediate filaments. (b) The contractile ring is made largely of microtubules and actin filaments. (c) The contractile ring divides the nucleus in two. (d) The mitotic spindle helps segregate the chromosomes to the two daughter cells.

Which of the following statements most correctly describes meiosis? (a) Meiosis involves two rounds of DNA replication followed by a single cell division. (b) Meiosis involves a single round of DNA replication followed by four successive cell divisions. (c) Meiosis involves four rounds of DNA replication followed by two successive cell divisions. (d) Meiosis involves a single round of DNA replication followed by two successive cell divisions.

Which of the following things is NOT true about the plus (+) end of microtubules? a) They are fastest growing b) Kinesin goes toward them c) They tend to be associated with GTP d) They tend to be associated with centrosomes e) They are a site of tubulin polymerization

Which of the following would likely be the best anti-cancer drug? a) A drug that promoted CDK activity b) A drug that suppressed DNA repair c) A drug that inhibited cadherin function d) A drug that inhibited APC e) A drug that suppressed apoptosis

Which type of molecule is LEAST likely to be found in a eukaryotic cell membrane? a) Phospholipid b) Cholesterol c) Glycoprotein d) Peptidoglycan

Which word or phrase below best describes the phase in mitosis depicted in Figure Q18-41? (a) anaphase (b) prometaphase (c) S-phase checkpoint (d) metaphase

_________ triggers the separation of sister chromatids by promoting the destruction of cohesins. (a) Adenomatous Polyposis Coli (b) Anaphase Prevention Complex (c) Adenomatous Promoting Complex (d) Anaphase Promoting Complex

__________________ join the intermediate filaments in one cell to those in the neighboring cell. __________________ anchor intermediate filaments in a cell to the extracellular matrix. __________________ involve cadherin connections between neighboring cells and are anchorage sites for actin filaments. __________________ permit the passage of small molecules from one cell to its adjacent cell. __________________ prevent the leakage of molecules between adjacent cells. adherens junctions gap junctions highway junctions desmosomes hemidesmosomes tight junctions

DESMOSOMES HEMIDESMOSOMES ADHERENS JUNCTIONS GAP JUNCTION TIGHT JUNCTIONS

Place the following cell that has the shortest half-life? a. epidermal cell b. nerve cell c. cells in bone matrix d. red blood cell e. cell lining the gut

'Ischemia' is the medical term for loss of blood flow to tissues. Ischemia deprives affected tissues of nutrients and oxygen. The cells in these tissues eventually undergo necrotic cell death. Which of the following is TRUE in cells undergoing ischemic cell death? a) Pro-apoptotic proteins (e.g. Bax) accumulate in the mitochondrial cell membrane, and the mitochondria then release cytochrome c into the cytoplasm. b) Caspases degrade cytoskeletal and other proteins. c) Protein complexes called 'apoptosomes' form and activate caspases. d) All of the above e) None of the above

A preparative period of the cell cycle called _________ consists of three subphases. (a) G1 (b) S (c) G2 (d) M (e) Interphase

ATP... a) is an important acceptor of phosphate from kinases. b) is not usually generated in the mitochondrial matrix. c) is synthesized by cytochrome c in a reaction that couples transmembrane proton flow to ADP phosphorylation. d) all of the above e) none of the above

Archaea are a type of... a) Bacteria b) Eukaryotic cell c) Plant d) Animal e) None of the above

Assuming memory formation requires activation of the PKA pathway leading to CREB phosphorylation, which of the following pills might make you smart? a) An adenylyl cyclase antagonist b) A MAP Kinase antagonist c) A Guanylyl cyclase agonist d) An inhibitor of Ras e) A phosphodiesterase inhibitor

Elevation of intracellular inositol trisphosphate (IP3) results in a release of Ca2+ from which of the following organelles? a) peroxisome b) lysosome c) mitchondiron d) nucleus e) smooth endoplasmic reticulum

If you were to clone yourself, which of the following would be TRUE? a) The clone would be the same age as you. b) The clone would have your memories. c) The clone's genome would have the same epigenetic modifications. d) All of the above. e) None of the above.

Induced pluripotent stem (iPS) cells ______________________. (a) are created by the expression of a set of foreign genes that are absent in the organism (b) require a supply of donor egg cells, such as embryonic stem cells (c) can differentiate into a greater variety of adult tissues than embryonic stem cells (d) are created by nuclear transplantation (e) none of the above

Now imagine that the tumor (described in question #41) is removed, and the tumor cells are studied in detail. Which of the following things do you think is most likely to be TRUE? a) The tumor cells show decreased cyclin/CDK activity b) The tumor cells have mutations that inactivate the CDK1 gene promoter c) Microtubules in the tumors cells cannot form properly d) The tumor cells have become prokaryotic e) None of the above is likely to be true

The KDEL sequence, found on luminal proteins of the ER, is responsible for (A) translocation of proteins into the ER lumen (B) insertion of proteins into the membrane of the ER (C) quality control in the ER (D) recognition by signal peptidase of the signal sequence (E) retrieval of ER luminal proteins from the Golgi

The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that is encoded by a proto-oncogene. Which of the following is therefore TRUE? a) Mutations that disrupt EGFR's ability to autophosphorylate will likely cause cancer. b) Mutations that disrupt EGFR's ability to dimerize will likely cause cancer. c) Mutations that delete the EGFR gene will likely cause cancer. d) All of the above. e) None of the above.

The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that is often mutated in tumor cells. Which of the following is therefore TRUE? a) Mutations that disrupt EGFR's ability to autophosphorylate will likely cause cancer. b) Mutations that disrupt EGFR's ability to dimerize will likely cause cancer. c) Mutations that delete the EGFR gene will likely cause cancer. d) All of the above. e) None of the above.

The level of active mitotic CDK rises and falls during the cell cycle. Which of the following best explains why the levels of active mitotic CDK fall? a) Transcription of cyclin stops after activation of P53. b) Polyubiquitination of APC triggers degradation of CDK. c) Active CDK stimulates a phosphatase that dephosphorylates CDK. d) APC degrades securin, which allows separin to degrade cohesions holding sister chromatids together, which allows anaphase to begin. e) Active CDK activates anaphase promoting complex, causing polyubiquitination of cyclin.

The loss of ______ stimulates the release of cytochrome c from mitochondria and ultimately leads to _______. a) Calcium - contact inhibition b) mitogens - mitosis c) survival factors - metastasis d) survival factors - cell necrosis e) survival factors - apoptosis

The movement of water soluble molecules through cell membranes, from higher to lower concentrations, by attachment to a carrier protein, describes A) diffusions B) Osmosis C) Pinocytosis D) Active transport E) Facilitated diffusion

What are the possible way(s) in which a cell can inhibit cell division? a) The non-phosphorylation of cyclin-Cdk. b) The activation of p53 protein leading to the transcription of the gene that encodes for the Cdk inhibitor protein, p21. c) The absence of cyclin. d) An absence of a mitogen that binds to a mitogen receptor. e) All of the above.

What is "vascular endothelial growth factor"? a) A protein encoded by a tumor suppressor gene b) A substance secreted by blood vessels that promotes tumor growth c) Another name for 'avastin.' d) All of the above. e) None of the above.

Where are nucleic acids found in cells? a) The nucleus b) The cytoplasm c) Associated with ribosomes d) In organelles e) All of the above

Which of the following is NOT a single cell? a) A human sperm b) A protozoan c) A neuron d) An unfertilized chicken egg e) A virus

Which of the following is NOT true? a) All organisms are composed of one or more cells b) Cells arise from other cells c) All cells contain DNA d) All cells contain ribosomes e) All of the above are true

Which of the following is TRUE about stem cells? a) Stem cells are terminally differentiated. b) Stem cells do not express any genes. c) Stem cells have no epigenetic modifications. d) Stem cells are found only in embryos. e) Stem cells are capable of 'self-renewal' (replacing themselves).

Which of the following is probably NOT true? a) MMPs degrade collagenase b) MMP activity requires SNARE-mediated exocytosis c) Mutations that cause increased MMP enzymatic activity are common in tumor cells d) MMP proteins are produced by endothelial cells (the cells that make blood vessels) during angiogenesis e) MMP proteins bind to and regulate the activity of cyclin-dependent kinases

Which of the following is true of the movement of cilia and flagella in eukaryotes? a) It produces ATP b) It is the result of a rotating motion c) It is identical to that of bacterial flagella d) It is driven by a proton gradient e) It results from one microtubule pair sliding along a neighboring microtubule pair

Which of the following statements about Rb protein is true? a) Rb is a growth factor receptor that is phosphorylated by active CDK-cyclin complexes. b) P53 phosphorylates Rb, causing it to become inactive and allowing expression of genes required for cell proliferation c) Phosphorylation of Rb protein inhibits cell proliferation. d) All of the above are true. e) None of the above are true.

Why do some stem cells become epithelial cells? a) Transcription factors like jun are activated by MAP kinases b) Laminin triggers creation of islet-like structures c) Because of they are induced pluripotent stem cells d) Stem cells can't become epithelial cells e) Because some stem cells express genes that are expressed mainly in epithelial cells.

will combat infection A. fibroblast B. Schwann cells C. macrophage d. blood vessels e. lymphocytes

Place the following in order of their replacement times, from shortest to longest. A. epidermal cell B. nerve cell C. bone matrix D. red blood cell E. cell lining the gut

E, A, D, C, B,

Before chromosomes segregate in M phase, they and the segregation machinery must be appropriately prepared. Indicate whether the following statements are true or false. If false, change a single noun to make the statement true. A. Sister chromatids are held together by condensins from the time they arise by DNA replication until the time they separate at anaphase. B. Cohesins are required to make the chromosomes more compact and thus to prevent tangling between different chromosomes. C. The mitotic spindle is composed of actin filaments and myosin filaments. D. Microtubule-dependent motor proteins and microtubule polymerization and depolymerization are mainly responsible for the organized movements of chromosomes during mitosis. E. The centromere nucleates a radial array of microtubules called an aster, and its duplication is triggered by S-Cdk. F. Each centrosome contains a pair of centrioles and hundreds of γ-tubulin rings that nucleate the growth of microtubules

FALSE FALSE FALSE TRUE FALSE TRUE

The cell cycle consists of an alternation between __________________, which appears as a period of dramatic activity under the microscope, and a preparative period called __________________, which consists of three phases called __________________, __________________, and __________________. During M phase, the nucleus divides in a process called __________________, and the cytoplasm splits in two in a process called __________________. The cell-cycle control system relies on sharp increases in the activities of regulatory proteins called __________________, or __________________, to trigger S phase and M phase. Inactivation of __________________ is required to exit from M phase after chromosome segregation. APC G2 phase metaphase Cdks interphase microtubules condensation intraphase mitosis cyclin-dependent kinases kinesins myosins cytokinesis M phase S phase G1 phase M-Cdk S-Cdk G1-Cdk meiosis

M phase interphase G1 phase S phase G2 mitosis cytokinesis cyclin-dependent kinases Cdks M-Cd.

Plants are sedentary and thus their cells have different needs from those of cells found in motile animals. For example, in plant cells, __________________ generates the turgor pressure that drives cell growth. Plants have cell walls, but cell growth is possible in the developing tissue because the __________________ cell walls are expandable. The __________________ cell walls are deposited once growth has stopped, and can be specially adapted to their function. Fibers made from __________________ (the most abundant organic macromolecule on Earth) are found in plant cell walls, and provide tensile strength. In woody tissues, the __________________ in the cell walls makes the tissue more rigid and waterproof. The deposition of the cell wall is directed by the __________________ cytoskeleton. actin lignin pectin cellulose membranous primary collagen microtubule secondary epidermis nuclear tertiary lamin osmosis

OSMOSIS PRIMARY SECONDARY CELLULOSE LIGNIN MICROTUBULE

Gregor Mendel studied pea plants and developed some very important ideas about how genes are inherited. These studies used plant strains that were true breeding and always produced progeny that had the same __________________ as the parent. These strains were true breeding because they were __________________ for the gene important for a specific trait. In other words, for these true-breeding strains, both chromosomes in the diploid pea plant carried the same __________________ of the gene. Mendel started out examining the inheritance of a single trait at a time, and then moved on to examining two traits at once in a __________________ cross. His studies examining the inheritance of two traits in one cross allowed him to discover what is now known as Mendel's law of __________________ assortment. Geneticists can study the inheritance of specific traits in humans by analyzing a __________________, which shows the phenotypes of different family members over several generations for a particular trait. allele genotype monohybrid chromosome heterozygous pedigree dependent homozygous phenotype dihybrid independent segregation

PHENOTYPE HOMOZYGOUS ALLELE DIHYBRID INDEPENDENT PEDIGREE

A chromosomal translocation that will swap the inhibitory domain of c-Abl with an unrelated protein and thus constitutively activates Abl tyrosine kinase activity will promote tumorigenesis. (a) True (b) False

TRUE

A mutation in EGFR that constitutively increases its tyrosine kinase activity will promote tumorigenesis. (a) True (b) False

TRUE

A mutation in the promoter of Wnt gene, causing the Wnt protein to be transcribed and translated at an abnormally high level will promote certain cancers. (a) True (b) False

TRUE

A mutation on the small GTPase Ras that hampers GTP hydrolysis makes it oncogenic. (a) True (b) False

TRUE

A mutation that introduces a stop codon immediately after the start codon of Adenomatous Polyposis Coli (APC) gene will promote certain cancers. (a) True (b) False

TRUE

Is the following statement true or false? After the nuclear envelope breaks down, microtubules gain access to the chromosomes and, every so often, a randomly probing microtubule captures a chromosome and ultimately connects to the kinetochore to become a kinetochore microtubule of the spindle.

TRUE

Are the statements below true or false? A. Statement 1: Generally, in a given organism, the S, G2, and M phases of the cell cycle take a defined and stereotyped amount of time in most cells. B. Statement 2: Therefore, the cell-cycle control system operates primarily by a timing mechanism, in which the entry into one phase starts a timer set for sufficient time to complete the required tasks. After a given amount of time has elapsed, a molecular "alarm" triggers movement to the next phase.

True False

For each of the following sentences, choose one of the options enclosed in square brackets to make a correct statement. Starting with a single diploid cell, mitosis produces [two/four] [identical/different] [haploid/diploid] cells, whereas meiosis yields [two/four] [identical/different] [haploid/diploid] cells. This is accomplished in meiosis because a single round of chromosome [replication/segregation] is followed by two sequential rounds of [replication/segregation]. Mitosis is more like meiosis [I/II] than meiosis [I/II]. In meiosis I, the kinetochores on sister chromatids behave [independently/coordinately] and thus attach to microtubules from the [same/opposite] spindle. The cohesin-mediated glue between [chromatids/homologs] is regulated differently near the centromeres than along the chromosome arms. Cohesion is lost first at the [centromeres/arms] to allow segregation of [chromatids/homologs] and is lost later at the [centromeres/arms] to trigger segregation of [chromatids/homologs].

Two identical diploid fout different haploid replication segregation ii I coordinately same chromatids arms homologs centromeres chromatids

By definition, procaryotic cells do not possess __________. a) a nucleus b) ribosomes c) a reason to live d) frizzy red hair e) a juice box

During fertilization in humans, _______________________. (a) a wave of Ca2+ ions is released in the fertilized egg's cytoplasm. (b) only one sperm binds to the unfertilized egg. (c) a sperm moves in a random fashion until it encounters an egg. (d) several sperm pronuclei compete in the cytoplasm to fuse with the egg nucleus.

Which of the following statements about the cell cycle is false? (a) Once a cell decides to enter the cell cycle, the time from start to finish is the same in all eukaryotic cells. (b) An unfavorable environment can cause cells to arrest in G1. (c) A cell has more DNA during G2 than it did in G1. (d) The cleavage divisions that occur in an early embryo have short G1 and G2 phases.

Progression through the cell cycle requires a cyclin to bind to a Cdk because _________. (a) the cyclins are the molecules with the enzymatic activity in the complex. (b) the binding of a cyclin to Cdk is required for Cdk enzymatic activity. (c) cyclin binding inhibits Cdk activity until the appropriate time in the cell cycle. (d) without cyclin binding, a cell-cycle checkpoint will be activated.

b)when cells enter G0

The regulatory component of MPF, called _______, has a stimulatory effecr on MPF activity abd plays a part in regulating interactions with its substrates (a) PI3K (b) APC (c) p53 (d) cyclin

Many features of __________________ cells make them suitable for biochemical studies of the cell-cycle control system. For example, the cells are unusually large and are arrested in a __________________-like phase. When the cells are triggered to resume cycling, the cell divisions have especially __________________ G1 and G2 phases and occur __________________. Studies with Xenopus eggs identified a partly purified activity called __________________ that drives a resting Xenopus oocyte into M phase. MPF activity was found to __________________ during the cell cycle, although the amount of its kinase component, called __________________, remained constant. The regulatory component of MPF, called __________________, has a __________________ effect on MPF activity and plays a part in regulating interactions with its __________________s. The components of MPF are evolutionarily __________________ from yeast to humans, so that the corresponding human genes are __________________ to function in yeast. able hexokinase short asynchronously inhibitory sperm Cdk long steady conserved M stimulatory cyclin maturation promoting factor substrate divergent oscillate synchronously egg PI 3-kinase ubiquitin fibroblast regulin unable G1 S uniform G2

egg G2 short synchronously maturation promoting factor oscillate Cdk, cyclin, stimulatory substrates conserved able

For each of the following sentences, fill in the blanks with the best word or phrase selected from the list below. Not all words or phrases will be used; each word or phrase may be used more than once. To reproduce sexually, an organism must create haploid __________________ cells, or __________________, from diploid cells via a specialized cell division called __________________. During mating, the father's haploid cells, called __________________ in animals, fuse with the mother's haploid cells, called __________________. Cell fusion produces a diploid cell called a __________________, which undergoes many rounds of cell division to create the entire body of the new individual. The cells produced from the initial fusion event include __________________ cells that form most of the tissues of the body as well as the __________________-line cells that give rise to the next generation of progeny. allele germ pollen bivalent meiosis somatic eggs mitosis sperm gametes pedigree zygote

germ gametes meiosis sperm eggs zygote somatic germ

The survival, __________________, and size of each cell in an animal are controlled by extracellular signal molecules secreted by neighboring and distant cells. Many of these signal molecules bind to a cell-surface __________________ and trigger various intracellular signaling pathways. One class of signal molecules, called __________________, stimulates cell division by releasing the molecular brakes that keep cells in the __________________ or __________________ phase of the cell cycle. Members of a second class of signal molecules are called __________________, because they stimulate cell growth and an increase in cell mass. The third class of signal molecules, called __________________, inhibits __________________ by regulating members of the __________________ family of proteins. In addition to such stimulatory factors, some signal proteins such as __________________ act negatively on other cells, inhibiting their survival, growth, or proliferation. anaphase differentiation myostatin annihilation G0 nourishment apoptosis G1 nutrition arrestase G2 phosphatases Bcl2 growth factors proliferation biosynthetic interphase receptor cascades ligand S caspase M survival factors Cdk mitogens transcription cyclin

proliferation receptor mitogens G0 or G1 growth factors survival apoptosis Bcl2 myostatin

Is the following statement true or false? Somatic cells leave no progeny and thus, in an evolutionary sense, exist only to help create, sustain, and propagate the germ cells.

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