BIOL 2170 Exam 3 Prep
Failure to recover a specific band in a gel made after PCR can be attributed to: a. inappropriate design of primers b. inappropriate numbers of cycles for amplification c. inappropriate annealing temperature used for specific primers d. All of these choices are correct.
D
If cells did not have actin, they would be unable to: a. maintain shape b. connect properly to neighboring cells c. organize proteins associated with the cytoplasmic membrane d. All of these choices are correct.
D
prophase
- Chromosomes become visable, nuclear envelop dissolves, spindle forms - chromosomes condensed - centrosomes are producing microtubules - centrosomes migrate to opposite poles
prophase I
- DNA condenses - homologous chromosomes undergo synapsis (gene for gene pairing) - each homologous chromosome pair forms a bivalent - chromosomes continue to shorten; chiasmata becomes apparent - nuclear envelope breaks down
interphase
- DNA replication and cell growth - includes S phase, G1 phase, and G2 phase - takes 12-18 hours
G1 phase
- Gap 1 phase of the eukaryotic cell cycle; falls between the end of cytokinesis and the start of DNA synthesis. - protein synthesis takes place
G2 phase
- Gap 2 phase of the eukaryotic cell cycle; falls between the end of DNA synthesis and the beginning of mitosis. - cell gets ready for mitosis
anaphase
- Phase of mitosis in which the chromosomes separate and move to opposite ends of the cell - sister chromatids fully separate
prometaphase
- The second stage of mitosis, in which the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the chromosomes. - nuclear envelope begins to break down
G0 phase
- cells not actively dividing - dormant cells
telophase
- chromosomes decondense - nuclear envelopes re-form around segregated chromosomes
telophase I (and cytokineses)
- development of nuclear membrane - separate into two cells
meiosis I
- homologous chromosomes separate from each other - reduce number of chromosomes by half
metaphase I
- homologous pairs line up in center - paternal and maternal chromosome parts do not always match up for each pair
M phase
- includes mitosis and cytokinesis - takes 1-2 hours
meiosis II
- sister chromatids separate - similar to mitosis
anaphase I
- spindles shorten - chromosomes separate, but not down the middle
cytokinesis
- the parent cell divides into two daughter cells - (animal cells) a contractile ring forms --> a ring of actin filaments - (plant cells) a cell plate forms; a pragmoplast forms
meiosis
- two rounds of nuclear division - result in 4 daughter cells (haploid gametes) - makes sexual reproduction possible - each daughter cell is genetically unique
During PCR, where does the energy come from that adds the nucleotide to the growing DNA strand? a. the incoming nucleotides b. the primers c. the elevated temperature of the PCR reaction d. Taq polymerase e. ATP
A
Gap junctions and plasmodesmata have what feature in common? a. They both allow direct transport of materials between cells. b. They both are made up of protein subunits located in the plasma membrane. c. They are both found in plant cells. d. They both attach to the cytoskeleton.
A
If you wanted to prevent the movement of particles through the space between animal cells, which junction would you use? a. tight junctions b. adherens junctions c. desmosomes d. hemidesmosones
A
In circular DNA, the DNA molecule is not shortened during each round of replication. a. true b. false
A
A daughter strand of DNA produced during chromosome replication can be composed of leading and lagging strands from different replication bubbles. a. true b. false
A
A graduate student wants to create a recombinant DNA molecule and introduce this to bacteria. What is the proper order of steps that he should follow? a. choose plasmid/donor DNA → cut with restriction enzymes → join fragments via DNA ligase → transform bacteria b. transform bacteria → choose plasmid/donor DNA → join fragments with DNA ligase c. cut plasmid/donor DNA with restriction enzymes → transform bacteria → isolate donor DNA/plasmid → join fragments with DNA ligase d. choose plasmid → cut with restriction enzymes → join fragments with DNA ligase → introduce donor DNA → transform bacteria e. join plasmid and donor DNA using DNA ligase → cut with restriction enzymes → transform bacteria
A
A researcher is evaluating the expression of p53 in cells she is culturing in the laboratory. She notices that in a small group of cells, high levels of phosphorylated p53 occur in the nuclei. What can she deduce about these cells? a. These cells likely contain damaged DNA. b. Within these cells, the cell cycle has been halted at the G2/M transition. c. These cells are normal. d. These cells have entered meiosis. e. These cells have entered mitosis.
A
A zygote is: a. diploid b. haploid c. polyploid d. monoploid
A
Cells with cilia or flagella rely mainly on ____________ to facilitate their movement. a. microtubules b. microfilaments c. intermediate filaments
A
Could melanin granules be moved by dyenin and kinesin along an actin microfilament? a. No, these motor proteins are specific to microtubules and cannot move along microfilaments. b. Yes, motor proteins all use ATP to cause a conformation change. c. Yes, melanin granules would be moved by these motor proteins along microfilaments.
A
Macrophage cells undergo a process called phagocytosis in which material is brought into a cell in the form of membrane vesicles and then transported along microtubules toward the cell center. Assuming that the centrosome is near the cell center, you can predict that these vesicles are moving to the _____ end of microtubules using the motor protein _____. a. minus end; dyenin b. plus end; kinesin c. plus end; dyenin d. minus end; kinesin
A
Muscle cells in the mammalian heart are multinucleate, meaning that multiple nuclei are present in the cytoplasm of a large cell. Predict what is different about the cell cycle in a muscle cell. a. Cytokinesis does not occur. b. The G1 and G2 phases are extended. c. S phase happens twice. d. M phase is inhibited.
A
Nondisjuction can occur in both mitosis and meiosis. a. true b. false
A
Predict what would happen if an embryonic cell switched from expressing E-cadherin to N-cadherin. a. The cell would leave the epidermis and adhere to neural cells. b. The cell would become a neural cell. c. The cell would die. d. There would be no effect.
A
Predict what would happen if crossing over between homologous chromosomes occurred as part of mitosis. a. Daughter cells would not be genetically identical. b. Daughter cells would be genetically identical. c. Daughter cells would be haploid. d. There would be no effect, because sister chromatids separate in anaphase.
A
RNA is involved in which cellular processes? a. All of these choices are correct. b. transcription c. translation d. DNA replication
A
The dermis of mammalian skin, including that of humans, contains a large amount of extracellular matrix proteins, including collagen and elastin. As a person ages, the amount of elastin in the dermis declines. Which of the cell types is likely to be the cause of this change in the dermis of the skin? a. fibroblasts b. keratinocytes c. melanocytes d. epidermal cells
A
The division of genetic material in a eukaryotic cell is called: a. mitosis b. binary fission c. replication d. cytokinesis
A
The division of the cell's cytoplasm in a eukaryotic cell is known as: a. cytokinesis b. both cytokinesis and mitosis c. cell fission d. mitosis
A
The epidermis contains several layers and receives its nutrients from the dermis by diffusion. What explains why the outermost layers of the epidermis consist of dead cells? a. One of the major functions of the epidermis is forming a waterproof barrier. Once that barrier is formed, nutrients cannot pass through it and the cells beyond that layer die. b. The protective function that the epidermis carries out is better served by having a layer of dead cells. c. UV light cannot penetrate as easily through dead cells as it can through live cells. d. None of these answers are correct.
A
The name of the technique used to amplify specific sequences of DNA is: a. the polymerase chain reaction (PCR) b. restriction c. Southern blot d. electrophoresis e. hybridization
A
Trisomy of the X chromosome has little effect on the health, whereas trisomy of any of the autosomes has significant detrimental developmental effects. What could account for this difference in effect of trisomy between the X chromosome and any of the autosomes? a. The X chromosomes undergo X inactivation and thereby correct for the copy number difference. Autosomes do not undergo dosage compensation (the equalization of the numbers of each gene). b. The X chromosomes don't contain any genes required for basic development or health. Autosomes do contain such genes. c. The X chromosome is very small and contains very few genes. Autosomes are much bigger and contain many genes. d. X chromosomes end up in the polar bodies during meiosis and are not contained in the egg. Autosomes are contained in the egg.
A
What is the function of a centromere? a. to attach the sister chromatids to each other b. to attach chromosome to the spindle c. to organize the microtubules to form a spindle d. to attach the DNA to the plasma membrane
A
What is the name of the enzyme that separates the two strands of DNA during replication? a. helicase b. DNA ligase c. primase d. DNA polymerase e. topoisomerase
A
What would happen in a cell if its gene for alpha-tubulin was mutated so that it was unable to bind to its beta-tubulin? a. The cell would have no microtubules. b. The cell would have no microfilaments. c. The cell would be unaffected. d. The cell would have no intermediate filaments.
A
Which are the functions of cyclins? a. Cyclins activate kinases that regulate passage of cell cycle checkpoints. b. Cyclins function as tumor suppressor genes. c. Cyclins remain in constant concentrations in the cell at all times. d. Cyclins replicate DNA during S phase.
A
Which of the following is true regarding DNA replication of a linear chromosome? a. Both strands get shortened at opposite strands during replication. b. Only the lagging strand gets shortened during replication. c. Only the leading strand gets shortened during replication. d. Both strands get shortened at the same time during replication. e. Only the lagging strand gets shortened after every other round of replication.
A
Which of the following statements about viruses is true? a. None of the answer options is correct. b. Viruses are a type of prokaryotic cell. c. Viruses are the root cause of most, if not all, cancers. d. Human cancers have not been associated with viruses. e. Viruses contain multiple genes, and each of these genes is an oncogene.
A
Which of these cytoskeletal elements are present in animal cells but absent from plant cells? a. intermediate filaments b. microfilaments c. microtubules d. All of these choices are correct
A
Which statement is true regarding binary fission? a. DNA replication of the circular bacterial chromosome during binary fission is a bidirectional process, starting at one point but progressing in opposite directions. b. In binary fission, cell division is typically asymmetrical, with one daughter cell appearing much smaller than the other. c. Tubulin, rather than FtsZ, is responsible for cell division during binary fission. d. Proteins only anchor the original circular genome to the plasma membrane; the copy produced by DNA replication is free-floating.
A
Which statement is true regarding telomeres? a. Telomeres can contain repeated base sequences. b. Telomeres are enzymes that repair telomerases, which cap the end of linear chromosomes. c. Telomeres are repaired to the same extent in germ cells and somatic cells. d. Telomeres contain non-essential genes that are not necessary for cell survival. e. Telomeres are only a few base pairs in size.
A
Which statement regarding the S cyclin-CDK complex is true? a. It ensures that DNA is not replicated multiple times. b. It is responsible for the phosphorylation of other proteins. c. It is regulated solely by the action of p53. d. It is responsible for the degradation of nuclear membranes. e. It regulates the expression of histone proteins.
A
Would genetic recombination result if crossing over occurred between sister chromatids? a. No, because sister chromatids are genetically identical or nearly identical. b. No, because many genes are present along the entire length of the chromosome. c. Yes, because any rearrangement of DNA produces new combinations of alleles. d. Yes, because genetic diversity would decrease due to the loss of gene combinations.
A
A researcher is studying phases of the cell cycle in a population of cells during which there is an increase in the DNA content. This stage is most likely: a. G1 phase b. S phase c. cytokinesis d. mitosis
B
A skin cell in G2 of interphase has _____ as much DNA as it had in G1. a. half b. twice c. exactly d. one-fourth e. four times
B
At the end of mitosis the daughter cells are ________, whereas at the end of meiosis the daughter cells are __________. a. haploid; diploid b. diploid; haploid c. diploid; polyploid d. polyploid; haploid
B
Dyenin is a motor protein found attached to: a. intermediate filaments b. microtubules c. microfilaments d. lamin
B
How must spindle microtubules attach to chromosomes during prometaphase of meiosis I? a. Spindle microtubules from one pole attach to one kinetochore, and spindle microtubules from the other pole attach to the other kinetochore in a pair of sister chromatids, just like in mitosis. b. Spindle microtubules from one pole must attach to both kinetochores in a pair of sister chromatids. c. Microtubules attach at the centrosomes. d. Microtubules attach using their minus (slow assembling) ends. e. Microtubules attach at the chiasma.
B
In mammals, females have two copies of the X chromosome, whereas males have only one copy. Dosage compensation is accomplished in mammals by: a. males inactivating the X chromosome inherited from the mother in all the cells b. females randomly inactivating one of the X chromosome in all cells c. males expressing the X-encoded genes at 2 times the level of the expression in the female
B
In skin, the cells of the epidermis connect to the basal lamina through cellular junctions known as hemidesmosomes. Select the cytoskeletal element that helps maintain the integrity of this connection. a. microtubules only b. intermediate filaments c. microfilaments only d. both intermediate microtubules and microfilaments
B
Okazaki fragments are found on _________________ strand of the DNA. a. both the leading and lagging b. the lagging c. the leading d. the parental
B
Structures known as microvilli are associated with: a. adhesion to the extracellular matrix b. increased surface area for nutrient absorption c. communication between cells d. increased rates of cell division
B
What is the function of histone proteins? a. to attach sister chromatids together b. to package DNA in eukaryotic chromosomes c. to connect the chromosomes in the mitotic spindle d. to organize the microtubules that make up the spindle
B
What is the result of DNA ligase's action? a. DNA is broken up at specific sites. b. DNA fragments are joined together. c. DNA is condensed to chromosomes. d. DNA transcription occurs. e. DNA translation occurs.
B
What would happen to the variation between organisms in a population if their DNA polymerase did not have a proofreading function? a. The amount of variation would decrease. b. The amount of variation would increase. c. The amount of variation would stay the same.
B
Which one of the cytoskeletal elements is associated with providing the cell with mechanical strength? a. microfilaments b. intermediate filaments c. microtubules and microfilaments d. microtubules
B
Why are single-stranded binding proteins necessary for DNA replication? a. They provide the necessary energy needed to separate the two strands of DNA. b. They prevent the two parental strands from coming together again. c. They direct the primase where to lay down the primer. d. They direct where replication will start.
B
Why are telomeres a necessary component of linear chromosomes? a. They fix mistakes that are made during DNA replication. b. They maintain the length of a chromosome because DNA is shortened every time it is replicated. c. They direct where DNA synthesis will end. d. They direct where DNA synthesis will begin. e. None of these answer options is correct.
B
Why would a compound that interferes with bacterial cell wall synthesis be useful for treating a bacterial infection? a. It would prevent replication of DNA. b. It would limit growth of the bacterial population through cell division. c. It would prevent cells from becoming larger. d. It would prevent replication of DNA, and it would limit the spread of the infection.
B
All of these events happen during M phase except: a. formation of the spindle b. condensation of the chromosomes c. synthesis of DNA d. separation of sister chromatids
C
At which stage of the cell cycle could you see sister chromatids with a microscope? a. G2 b. G1 c. M d. S
C
Imagine that you are examining a mouse that does not produce basal lamina in the skin. How will this mouse be different from a normal, wild-type mouse? a. The dermis will be disorganized and lack blood vessels. b. The epidermis and dermis will be strongly connected. c. The cells of the epidermis would not be properly connected to form a water-resistant barrier. d. Cellular junctions will fail to form between the cells of the epidermis. e. All of these choices are correct.
C
In which phase of mitosis do chromosomes condense? a. anaphase b. telophase c. prophase d. metaphase
C
Microtubules that form the mitotic spindle extend out from the centrosome. Where would you expect to find the plus (fast-assembling) end of a spindle micrfotubule? a. toward the centrosome and toward the centrosome b. away from the centrosome and away from the kinetochore c. away from the centrosome and toward the kinetochore d. toward the centrosome and away from the kinetochore
C
Sexual reproduction results in an increase in genetic diversity because: a. during metaphase I, the bivalents line up in a random orientation so that gametes inherit a random set of maternally and paternally derived chromosomes. b. during prophase I, genes that are paternally and maternally derived recombine so that the gametes have chromosomes that are different from the parents' chromosomes. c. All of these choices are correct. d. during fertilization, the gametes that fuse are random so that a large number of chromosomal combinations are possible in the new organism.
C
The following enzymes play important roles in DNA replication: DNA polymerase, primase, ligase, helicase. In what order do they work during replication? a. DNA polymerase, helicase, primase, ligase b. primase, helicase, ligase, DNA polymerase c. helicase, primase, DNA polymerase, ligase d. ligase, helicase, DNA polymerase, primase e. DNA polymerase, primase, ligase, helicase
C
The main function of DNA polymerase is to add new nucleotides to the 3' end of a growing chain. What is the second role of this enzyme in DNA replication? a. synthesis of the RNA primer b. unwinding of the DNA duplex c. proofreading d. stabilizing strands of DNA at replication fork e. joining Okazaki fragments
C
What protein forms a contractile ring during cytokinesis in animal cells? a. kinesin b. DNA polymerase c. actin d. dyenin
C
What would happen in cell division if the cell was deficient in actin? a. The sister chromatids would not separate. b. The mitotic spindle would not form. c. The cell would not divide. d. The centromeres would remain unattached.
C
What would happen to the daughter cells if the G2 phase of the parent cell is shortened? a. The cells would be larger than normal. b. The cells would not undergo cytokinesis. c. The cells would be smaller than normal. d. The cells would be missing chromosomes.
C
Which answer choice is true about the motor proteins myosin and kinesin? a. They both move cargo along microtubules. b. They both move along microfilaments. c. They both use the energy of ATP. d. They both move chromosomes along spindle fibers during mitosis.
C
Which is the correct decreasing order of cytoskeletal elements from largest filament diameter to smallest filament diameter? a. microtubules, microfilaments, intermediate filaments b. microfilaments, microtubules, intermediate filaments c. microtubules, intermediate filaments, microfilaments d. intermediate filaments, microfilaments, microtubules
C
Which of the following are true regarding CDKs? a. CDKs are active except when they bind to cyclins. b. CDKs are active in cells that enter G0 phase of the cell cycle. c. The levels of CDKs change with the cell cycle. d. Loss of CDK activity would lead to cancer.
C
Why does meiosis result in more genetic variation that can be explained by mutation alone? a. meiosis II b. The egg and sperm have more chromosomes. c. crossing over d. Not all DNA gets replicated.
C
________ is not a cellular function of microfilaments. a. Muscle contraction b. Transport of vesicles c. Movement of motile cilia d. Formation of daughter cells during cytokinesis
C
metaphase
Chromosomes line up in the middle of the cell
A eukaryotic chromosome has ____________ origin(s) of replication, and a bacterial chromosome has ____________ origin(s) of replication. a. many, many b. one, many c. one, one d. many, one
D
A gene associated with promoting normal cell division is called: a. a tumor suppressor b. an oncogene c. a proto-oncogene or a tumor suppressor d. a proto-oncogene
D
A patient in a physician's office has a deep cut, and as it is being stitched up, a sample of tissue is taken for testing. Analysis of the tissue reveals it has few cells, surrounded by a large amount of extracellular matrix proteins with some blood vessels, sweat glands, and nerve cells. What kind of tissue is this? a. The tissue is most likely epidermis and should also have many v keratinocytes and melanocytes. b. The tissue is most likely epidermis and should also have some fibroblasts but few keratinocytes and melanocytes. c. The tissue is most likely dermis and should also have many keratinocytes and melanocytes. d. The tissue is most likely dermis, and should also have some fibroblasts, but few keratinocytes and melanocytes.
D
A researcher is studying a population of mutant fibroblasts that fail to flatten and attach to the extracellular matrix proteins on a flat surface. This is likely the result of the result in mutations in genes encoding: a. components of the cytoskeleton b. components of microvili c. components of motor proteins d. components of cell junctions
D
Cilia: a. are specialized organelles found in some epithelial cells. b. are used by epithelial cells to move substances along cell surfaces. c. can sometimes serve as a sensory function. d. All of these choices are correct.
D
During what step in meiosis do homologous chromosomes separate? a. prophase II b. anaphase II c. metaphase II d. anaphase I
D
Dynamic instability is the rapid assembly and disassembly of: a. both microfilaments and microtubules b. intermediate filaments c. microfilaments d. microtubules
D
Imagine that a doctor is culturing cells from a malignant melanoma and from a normal skin sample. How would you expect these two cell populations to differ? a. Malignant melanoma cells would have inactive telomerases, so their telomeres would shorten during successive rounds of replication. b. Normal skin cells would have telomeres that do not shorten during successive rounds of replication. c. Malignant melanoma cells would have telomeres that shorten during successive rounds of replication. d. Malignant melanoma cells would have active telomerases that constantly replenish and lengthen telomeres. e. Normal skin cells would have active telomerases that constantly replenish and lengthen telomeres.
D
In nerve cells, the centrosome is located near the nucleus. Vesicles move from near the nucleus to the end of long extensions (axons) along microtubules. Based on these two facts, it is possible to conclude that these vesicles are moving in the _____ direction on the microtubule using the motor protein _____. a. minus end; kinesin b. plus end; dyenin c. minus end; dyenin d. plus end; kinesin
D
In which phase of mitosis do sister chromatids separate? a. telophase b. prophase c. metaphase d. anaphase
D
Microvili are located on the ___________ of an intestinal cell. a. adjacent surface b. basolateral surface c. basement surface d. apical surface
D
Motor proteins cause movement by: a. harnessing energy from ATP b. undergoing a conformational change c. binding to the cytoskeleton d. All of these choices are correct.
D
The centrosome is: a. a region of the chromosome where sister chromatids are attached to each other b. a region of the chromosome where microtubules attach to chromosomes during mitosis c. a region of the chromosome where kinetochores attach d. the microtubule organizing center for the mitotic spindle
D
The natural loss of dead cells from the surface of your skin is a result of: a. loss of microvili b. loss of plasmodesmata c. increased expression of integrin genes d. breakdown of adherens junctions
D
What cellular process(es) is/are responsible for the increase in protein content associated with the gap phases of the cycle? a. glycolysis b. translation alone c. transcription alone d. both transcription and translation
D
What would happen to a cell if cyclin was constitutively made? a. Cell cycle proteins would be constitutively phosphorylated. b. Cyclin-dependent kinases would be constitutively activated. c. The cell would divide rapidly. d. All of the above.
D
What would happen to a cell that depends on motile cilia for movement if it had no actin? a. The cell would not be able to move because dyenin and kinesin could not work. b. The cell would not be able to move. c. The cell might be able to move if it used actin and myosin to change shape. d. Nothing; motile cilia contain microtubules, not microfilaments.
D
Which cell adhesion molecule is particularly good at attaching the cell to the basement membrane? a. actin b. catherins c. myosin d. integrins
D
Which represents a misconception about sister chromatids? a. Sister chromatids are also called homologous chromosomes. b. Sister chromatids are formed in the S phase of the cell cycle when the chromosome undergoes replication. c. Sister chromatids are identical or nearly identical DNA sequences. d. Sister chromatids are formed when the prokaryotic circular chromosome attaches at the plasma membrane. e. Sister chromatids are attached to each other at the centromeres.
D
Asexual reproduction occurs in: a. animal cells b. plant cells c. bacterial cells d. unicellular eukaryotes e. All of these choices are correct.
E
The point at which DNA synthesis is initiated is called the: a. primase b. replication fork c. primer d. start codon e. origin of replication
E
What is the difference between PCR and Sanger sequencing with regard to the materials needed to perform these reactions? a. DNA polymerase is needed in Sanger sequencing but not PCR. b. Primers are needed in Sanger sequencing but not PCR. c. DNA polymerase is needed in PCR but not Sanger sequencing. d. Primers are needed in PCR but not Sanger sequencing. e. Dideoxynucleotides needed in Sanger sequencing but not PCR.
E
What is true regarding chromosome replication in eukaryotes? a. None of the answer options is correct. b. Replication begins at one end of the chromosome and proceeds until it reaches the opposite end. c. In humans, it takes several days to replicate an entire chromosome. d. Replication bubbles remain distinct, isolated structures during chromosome replication and never fuse with one another. e. During chromosome replication, multiple origins of replication form for all DNA in a cell.
E
Which cellular conditions promote progession of the cell cycle? a. the accumulation of cyclins b. the expression and synthesis of cyclin proteins c. the activation of CDKs d. binding of cyclins to CDKs e. All of these choices are correct.
E
Why are primers needed for DNA replication? a. They help with the joining of Okazaki fragments. b. A tiny amount of RNA is needed to tell where genes are located. c. They help direct the placement of the telomeres. d. The primers help with the proofreading function of DNA polymerase. e. DNA polymerase can only add nucleotides to an existing chain.
E
Why are single-stranded binding proteins necessary for DNA replication? a. None of the answer options is correct. b. They direct where replication will start. c. They direct the primase where to lay down the primer. d. They provide the energy necessary to separate the two strands of DNA. e. They prevent the two parental strands from coming together again.
E
Plasmodesma
Major component: cell membrane Primary function: communication between plant cells
Gap junction
Major component: connexins Primary function: communication between animal cells
Desmosome
Major components: cadherins, intermediate filaments Primary function: cell-cell adhesion
Adherens Junction
Major components: cadherins, microfilaments Primary function: cell-cell adhesion
Tight junction
Major components: claudins, occludins Primary function: epithelial boundary
Hemidesmosome
Major components: integrins, intermediate filaments Primary function: cell-extracellular matrix adhesion
Microfilaments
Subunits: Actin monomers Major functions: - cell shape and support - cell movement (by crawling) - cell division (cytokinesis) - vesicle transport - muscle contraction
intermediate filaments
Subunits: diverse Major function: cell shape and support
Microtubules
Subunits: tubulin dimers Major functions: - cell shape and support - cell movement (by cilia, flagella) - cell division (chromosome segregation) - vesicle transport - organelle arrangement
S phase
The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated.
A mutation acquired by a bacterium will most likely be inherited by all daughter cells. a. true b. false
a. true
A proto-oncogene is a "normal" gene that, if mutated, can become an oncogene and lead to a cell becoming cancerous. a. true b. false
a. true
A transgenic organism is synonymous with a genetically modified organism, as both can contain recombinant DNA. a. true b. false
a. true
An example of second-division nondisjunction is when sister chromatids fail to separate during anaphase of meiotic cell division. a. true b. false
a. true
DNA polymerase requires both a template and a free 3' end to elongate a nucleotide chain. a. true b. false
a. true
Denaturization of DNA is a necessary step in Southern blotting procedure because it separates double stranded DNA into single stranded DNA. a. true b. false
a. true
Evidence exists (especially in dinoflagellates) that mitosis evolved from binary fission. For example, in certain eukaryotic cells during mitosis, DNA is attached to the membrane of the nucleus (much like a circular chromosome of a bacterium is attached to the plasma membrane). a. true b. false
a. true
Some types of leukemia are the result of constitutively active (i.e., "always on") growth factor receptors. a. true b. false
a. true
Trisomy 21 (Down Syndrome) is one of only a few examples of an autosomal trisomy in which the fetus develops to term and is born alive. a. true b. false
a. true
All cancers are caused by viruses. a. true b. false
b. false
During DNA replication, the leading strand contains Okazaki fragments. a. true b. false
b. false
First-division nondisjunction will only yield gametes with an extra chromosome, whereas second-division nondisjunction will only yield gametes missing a chromosome. a. true b. false
b. false
If a restriction site of AatII is 5′-GACGTC -3′ then 3′-GACGTC-5′ is also an AatII restriction site. a. true b. false
b. false
Massive parallel sequencing techniques can reliably determine the sequence of hundreds of base pairs but require more time than Sanger sequencing. a. true b. false
b. false
Okazaki fragments are ligated to form a continuous DNA molecule after replication is completed. a. true b. false
b. false
Restriction enzymes are an essential component of PCR. a. true b. false
b. false
Telomerase activity in stem cells is very low. a. true b. false
b. false
The first step of PCR, called annealing, is performed by DNA polymerase. a. true b. false
b. false
The semiconservative model of DNA replication means that each strand of the double helix consists of some newly synthesized DNA and some parental DNA. a. true b. false
b. false
metaphase II
chromosomes align in center of cell
prophase II
nuclear envelope breaks down
telophase II and cytokinesis
nuclear envelope reforms and cytoplasm divides
anaphase II
sister chromatids separate
prometaphase II
spindles attach to kinetochores
prometaphase I
spindles attach to kinetochores on chromosomes