Biology 203 Final Exam Prep

Which of the following statements are true descriptions of mutations? a. Point mutations can occur in any DNA sequence. b. Frameshift mutations can occur in any DNA sequence. c. Neutral mutations depend on the degeneracy of the genetic code. d. Deleterious mutations occur only in protein-coding sequences of DNA. e. All point mutations change the genotype and phenotype.

A is true, rest are false

Why can some insects walk on water? A. Because of the high heat capacity of water, requiring more energy for it to evaporate, thus allowing insects to walk. B. Because of the surface tension of water, resulting from the attraction between water molecules (cohesion) at the surface of the body of water (the liquid-air/gas interface). C. Because liquid water is more dense than ice, it is therefore more dense than insects, allowing them to walk. D. Because water ionizes which give rise to pH, the neutral pH of water allows insects to walk.

B. Because of the surface tension of water, resulting from the attraction between water molecules (cohesion) at the surface of the body of water (the liquid-air/gas interface).

Injecting a dose of a solution containing potassium ions (K+) into a person's blood can cause the heart to stop beating. This method is often used during open heart surgery. Using what you know about the Na+/K+-ATPase and electochemical gradients, why do you think an injection containing K+ ions leads to cardiac arrest? A. Cells typically have a high concentration of Na+ in the cytoplasm and a high concentration of K+ in the extracellular fluid. A potassium solution would disrupt the gradient and cause the cells to not function properly. B. Cells typically have a high concentration of K+ in the cytoplasm and a high concentration of Na+ in the extracellular fluid. A potassium solution would disrupt the gradient and cause the cells to not function properly. C. Cells typically have equal concentrations of Na+ and K+ in the cytoplasm and in the extracellular fluid. A potassium solution would disrupt the gradient and caus

B. Cells typically have a high concentration of K+ in the cytoplasm and a high concentration of Na+ in the extracellular fluid. A potassium solution would disrupt the gradient and cause the cells to not function properly.

If a cell had very low levels of Primase, how would DNA replication change? A. DNA replication would slow down; with low amounts of primase, DNA primers would be added to single-stranded DNA more slowly. DNA primers are required for the attachment of DNA Polymerase III. B. DNA replication would slow down; with low amounts of primase, RNA primers would be added to single-stranded DNA more slowly. RNA primers are required for the attachment of DNA Polymerase III. C. DNA replication would stop because Primase is needed for synthesizing Okazaki fragments. Therefore, both strands of the DNA molecule would not undergo replication D. The rate of DNA replication would not change. Low amounts of primase would have no effect on DNA replication because this enzyme is not necessary for this process.

B. DNA replication would slow down; with low amounts of primase, RNA primers would be added to single-stranded DNA more slowly. RNA primers are required for the attachment of DNA Polymerase III.

1. Identify the process happening in the diagram below. 2. Identify each label in the diagram and its function.

1. Transcription initiation. There is a gene X that will be transcribed into an RNA transcript. 2. A - TATA binding protein/general transcription factorB - enhancerC - large amount of DNAD - mediatorE - RNA Pol IIF - regulatory transcription factor/transcription factor/activator A - TATA binding protein/general transcription factors are proteins that bind to the promoter region of the gene. They are necessary for transcription to occur, but do not provide regulation. They recruit other gTFs and RNA Pol II to initiate transcription. B - Enhancers are regulatory sequences of DNA that are far from the promoter and activate transcription. They can be upstream or downstream from the promoter, and even within introns. These sequences are recognized by proteins. D - Mediator is a complex of proteins that bind regulatory transcripton factors (proteins) and brings them into close proximity to promoter E - RNA Pol II is recruited to the promoter and catalyzes the synthesis of messenger RNA (mRNA) F - Regulatory transcription factors are proteins that bind to DNA regions called enhancers and promoter proximal elements and regulate when transcription will occur (transcription activation).

How many amino acids are encoded in this sequence? How do you know? 3' -A T A G G T A C C G T G A A A T T T G - 5'

5' -U A U C C A U G G C A C U U U A A A C - 3' = 3 AA

The human stomach contains a natural, carbohydrate-based antibiotic that probably protects a large portion of the population from various diseases caused by the bacterium Helicobacter pylori. This bacterium has been linked to peptic ulcers, gastritis, and stomach cancer. This naturally occurring antibiotic is described by researchers as having a terminal α-1, 4-linked N-acetylglucosamine (NAG), and it acts by inhibiting the biosynthesis of a major component of the cell wall in H. pylori. Researchers created a glycoprotein with a terminal NAG (that is, a protein with NAG attached to its end). Their hypothesis is that the terminal NAG, and not the protein component, is responsible for the damage to the cell wall in H. pylori. What would be the most appropriate control for testing this hypothesis?

B. Grow H. pylori in a test tube with a glycoprotein that has its terminal NAG removed.

Which of the following is most likely to lead to cancer? A. BRCA1 proteins being overproduced B. HER2 proteins being overproduced C. G1 cyclin being underproduced D. GDP being constantly bound to Ras

B. HER2 proteins being overproduced

Read the following sentences, and then choose one option below. I. "In this study, we tested the hypothesis that the cause of muscle mass loss after nerve damage is an increase in the protein TRB3." II. "In this study, we tested the hypothesis that treatment with an antibody that blocks the enzymatic activity of protein PAPP-A will reduce atherosclerotic plaque progression." A. Both I and II are hypotheses. B. I is a hypothesis, but II is a prediction. C. I is a prediction, but II is a hypothesis. D. Both I and II are predictions.

B. I is a hypothesis, but II is a prediction.

Recall from the "Mystery of the Newt" that a single rough-skinned newt killed three hunters after it got into their coffee pot. As the newt was boiled over the campfire, a substance on its skin called tetrodotoxin (TTX) contaminated the water to make a lethal brew. The newts store TTX in secretory vesicles inside gland cells, and secrete the toxin as a defense mechanism. When newts are stimulated to secrete TTX, predict which motor protein would deliver the vesicle to its destination in the cell and how? A. Kinesin walking towards the minus end of the microtubule will deliver vesicle to the lysosome. B. Kinesin walking towards the plus end of the microtubule will deliver vesicle to the plasma membrane. C. Dynein walking towards the minus end of the microtubule will deliver vesicle to the lysosome. D. Myosin walking towards the plus end of the microtubule will deliver vesicle to the plasma membrane.

B. Kinesin walking towards the plus end of the microtubule will deliver vesicle to the plasma membrane.

An increase in phosphorylation levels of eIF-2 (eukaryotic initiation factor 2) has been observed in patients with neurodegenerative diseases such as Alzheimer's, Parkinson's, and Huntington's. What impact do you think this might have on protein synthesis? A. Protein synthesis would be increased due to post-translational modification. B. Protein synthesis would be inhibited due to post-translational modification. C. Protein synthesis would be increased due to chromatin remodeling. D. Protein synthesis would be decreased due to chromatin remodeling.

B. Protein synthesis would be inhibited due to post-translational modification.

Which enzyme makes transfer RNA (t-RNA)? A. DNA polymerase B. RNA polymerase C. Primase D. Aminoacyl t-RNA synthetase

B. RNA polymerase

Which cells are most likely to have the gene for making telomerase switched on? A. The nerve cells of a 55 year old man. B. The cells in a developing embryo C. The skin cells of a 28 year old person. D. The muscle cells of a woman who is 80 years old

B. The cells in a developing embryo

In a photosynthetic eukaryote, a thylakoid membrane protein involved in electron transport is nonfunctional. It was discovered that a positively charged amino acid was replaced with a negatively charged amino acid. How might this change affect photosynthesis?

B. The light capturing reactions will stop functioning.

A student has drawn this model to study for her exam. Which statement is TRUE about her model? A. The shape with the dark area represents a barrier preventing substances from entering. B. The shape with the dark area represents a pore to transport substances. C. The phospholipids are drawn with their heds and tails in the wrong orientation in the bilayer. D. Only two different types of macromolecules are represented in this model. E. All statements are true.

B. The shape with the dark area represents a pore to transport substances.

Cells use the sodium electrical gradient to perform many activities. What membrane protein is used to establish the sodium electrochemical gradient and how does it work? A. The sodium electrical gradient would be established by the voltage-gated sodium channel through facilitated diffusion. B. The sodium-potassium pump (Na+/K+-ATPase) establishes the sodium electrical gradient by using ATP to undergo conformational changes that result in moving three sodium ions out of the cell and two potassium ions into the cell. C. The sodium-potassium pump (Na+/K+-ATPase) establishes the sodium electrical gradient by using ATP to undergo conformational changes that result in moving two potassium ions out of the cell and three sodium ions into the cell. D. No membrane protein is required because lipid bilayers are highly permeable to sodium ions.

B. The sodium-potassium pump (Na+/K+-ATPase) establishes the sodium electrical gradient by using ATP to undergo conformational changes that result in moving three sodium ions out of the cell and two potassium ions into the cell.

In the figure below, which is the leading strand and which is the lagging strand? A. Top red strand is leading and bottom red strand is lagging. B. Top red strand is lagging and bottom red strand is leading. C. Both red strands are leading. D. Both red strands are lagging.

B. Top red strand is lagging and bottom red strand is leading.

In a ribosome, a mutation has changed a nucleotide in the ribosome's active site. The ribozyme cannot cause the formation of a covalent bond. Which of the following might be a reasonable explanation of how this might affect translation? A. Translation would continue, producing a full protein because ribozyme function is not needed for protein synthesis. B. Translation would continue, producing a series of free amino acids, all unattached because the ribozyme is unable to form peptide bonds. C. Translation would continue, producing a protein with no R-groups because the mutated ribozyme will cut off the R-groups on the amino acids. D. Translation would continue, producing a full protein because DNA, not ribosomes are needed to synthesize proteins.

B. Translation would continue, producing a series of free amino acids, all unattached because the ribozyme is unable to form peptide bonds.

In a 'pulse-chase' experiment, radioactively labeled amino acids are fed to a culture of bacteria, and then the bacteria are added to a culture of neutrophils (white blood cells). From earliest to latest, where would radioactive materials appear? A. Endoplasmic reticulum, Golgi, vesicles near the Golgi, vesicles near the cell surface. B. Vesicles near the cell surface, vesicles deeper in the cell, lysosomes, cytoplasm. C. Vesicles near the cell surface, vesicles deeper in the cell, Golgi, endoplasmic reticulum. D. None of the above

B. Vesicles near the cell surface, vesicles deeper in the cell, lysosomes, cytoplasm.

A mutation has changed a sequnce in the DNA of SLC24A5*2 to create a third allele. The coding sequence is (not writing all that). What would be the effect of this mutation?

B. a change in multiple amino acids of the protein

Chondrocytes are cells found in the cartilage in our joints. In some forms of osteoarthritis, destruction of the chondrocyte extracellular matrix is associated with a diseased endoplasmic reticulum. This finding supports the idea that _____. A. extracellular matrix material is easily damaged B. endoplasmic reticulum is involved in the synthesis of extracellular matrix C. Golgi apparatus is not involved with the synthesis of the extracellular matrix D. the extracellular matrix is a complex structure

B. endoplasmic reticulum is involved in the synthesis of extracellular matrix

The bacterium Bacillus anthracis, commonly known as anthrax, causes an often fatal disease that is also called anthrax. The U.S. Centers for Disease Control and Prevention (CDC) recommends that anyone who might have been exposed to anthrax begin treatment with the antibiotic ciprofloxacin, a DNA-synthesis inhibitor. For ciproflaxin to be useful, it must work: A. exclusively against telomerase B. exclusively against bacterial DNA synthesis proteins C. exclusively against eukaryotic DNA synthesis proteins D. against both bacterial and eukaryotic DNA synthesis proteins

B. exclusively against bacterial DNA synthesis proteins

What holds the quaternary (4o) structure of cellulose molecules together in bundles large enough to form fibers? A. glycosidic linkages B. hydrogen bonds C. the cell wall D. peptide bonds

B. hydrogen bonds

Why is the hydrolysis of a polymer like starch an exergonic reaction? These reactions ___. A. reduce entropy B. increase entropy C. require energy D. have a low activation energy

B. increase entropy

Alternative splicing during gene expression occurs _____. A. only outside the nucleus in eukaryotes B. only inside the nucleus in eukaryotes C. in both eukaryotes and prokaryotes D. only when mRNA is being translated in eukaryotes

B. only inside the nucleus in eukaryotes

Cell walls are used by many different organisms for protection from their environment and structural support. These cell walls must be insoluble in water; otherwise, they would dissolve the first time an organism got wet. Which of the following carbohydrates would you expect to be most soluble in water? A. chitin B. starch C. cellulose D. peptidoglycan

B. starch

A solution of starch at room temperature does NOT readily decompose to form a solution of simple sugars because __________ . A. the starch solution has less free energy than the sugar solution B. the activation energy barrier for this reaction cannot easily be surmounted at room temperature C. the hydrolysis of starch to sugar is endergonic D. starch cannot be hydrolyzed in the presence of so much water

B. the activation energy barrier for this reaction cannot easily be surmounted at room temperature

What provides the energy for the polymerization reactions in DNA synthesis? A. ATP B. the deoxyribonucleoside triphosphate substrates C. breaking the hydrogen bonds between complementary DNA strands. D. DNA polymerase

B. the deoxyribonucleoside triphosphate substrates

What provides the energy for the polymerization reactions in DNA synthesis? A. ATP B. the deoxyribonucleoside triphosphate substrates C. breaking the hydrogen bonds between complementary DNA strands D. DNA polymerase

B. the deoxyribonucleoside triphosphate substrates (DNTPS)

Muscle contraction is initiated when a section of a DHPR protein moves, allowing calcium ions to flow into a cell. The protein is said to act as a gate for calcium ions. This is an example of ___________. A. protein evolution B. the flexible nature of proteins C. the complex nature of proteins D. the quaternary structure of proteins

B. the flexible nature of proteins

The Hawaiian bobtail squid is able to glow from luminescent Vibrio fischeri bacteria held in its light organs. As it swims at night near the ocean surface, it adjusts the amount of light visible to predators below to match the light from the stars and moon. Predators have a hard time seeing the illuminated squid against the night sky. The bacteria glow in response to a molecule that regulates expression of genes involved in light-producing chemical reactions. The regulator controls production of the genes' mRNA. Therefore, the light-producing genes are under____. A. negative control B. transcriptional control C. translational control D. post-translational control

B. transcriptional control

Explain why a mating between a normal male and a female homozygous for a loss-of-function Bicoid mutation produces misshapen embryos, but the reciprocal cross produces normally patterned embryos.

Because bicoid is a maternal effect, this means that the mother's genotype controls the phenotype of her offspring. Offspring of a bicoid mutant homozygote mother are expected to have patterning defects, whereas offspring of a bicoid mutant homozygote father are expected to have normal patterning if the mother has at least one wild-type allele of the bicoid gene.

How would the following affect the expression of a regulon under negative control: a. a mutation that altered a repressor protein making it unable to bind b. a mutation of an operator

Because the same repressor protein is needed to regulate all genes in the regulon, a mutant repressor would be unable to bind to any operator in the regulon. This result is predicted to affect the expression of every regulon gene. In contrast, mutation of a single operator (which is the DNA) should affect only the gene(s) associated with that operator (i.e. operon) and no others.

Compare and contrast competitive inhibition and allosteric regulation.

Both competitive inhibition and allosteric regulation are a form of enzyme activity regulation. However, competitive inhibition involves a substance that is able to bind to an active site, preventing the intended substrate from binding and generally stopping the chemical reaction. Allosteric regulation, on the other hand, involves a substance binding to the allosteric site, and this can either activate or inhibit an enzyme.

What is the purpose of the 5' and 3' untranslated regions (UTRs)?

Both play a role in controlling translation and mRNA stability

Using your knowledge of the cell cycle and the following diagram, indicate which of the following statements are true. 1. Nonfunctional E2F protein will not lead to cancer, because E2F is needed to drive the cell into S-phase. 2. Overproduction of Rb will not lead to cancer, because Rb is a tumor suppressor stopping cell division. 3. Ras with a GTP that cannot be hydrolyzed will not lead to cancer because the cell is unable to turn off the signaling from the growth factors. 4. Nonfunctional phosphatase will not lead to cancer because G1 Cylin-Cdk cannot be activated. 5. Overexpression of MPF activity will lead to cancer, because MPF drives teh cell into M-phase.

C. 1, 2, and 4 only

If a double-stranded DNA sample was composed of 10 percent thymine, what would be the percentage of guanine? A. 10 B. 20 C. 40 D. 80

C. 40

In analyzing the number of different bases in a DNA sample, which result would be consistent with the base-pairing rules? A. A = C B. A + T = G + C C. A + G = C + T D. G = T

C. A + G = C + T

Refer to the figure below. After DNA denaturation and primer annealing in the polymerase chain reaction (PCR), what type of primer will they be added to? A. U, G, U, C, G, U, C added to a DNA primer B. U, G, U, C, G, U, C added to an RNA primer C. A, G, A, C, G, A, C added to a DNA primer D. A, G, A, C, G, A, C added to an RNA primer

C. A, G, A, C, G, A, C added to a DNA primer

Enzymes that readily break starch apart cannot hydrolyze the glycosidic linkages found in cellulose. Why is this logical? A. Starch is held together by hydrogen bonding, not covalent bonding. B. Cellulose molecules are highly branched, and enzymes are too bulky to fit. C. The geometry of the bonds is different, and the shapes of enzyme active sites are highly specific. D. Starch is held together by peptide bonds, not glycosidic linkages.

C. The geometry of the bonds is different, and the shapes of enzyme active sites are highly specific.

How does this mutation affect the amino acid sequences of SLC24A5*1 and SLC24A5*2?

C. The mutation causes a nonpolar amino acid in SLC24A5*1 to be substituted for a polar amino acid in SLC24A5*2.

A doctor injects a patient with what the doctor thinks is an isotonic saline solution. The patient dies, and an autopsy reveals that many red blood cells have been destroyed, leaving membrane fragments. Do you think the solution the doctor injected was really isotonic? A. Yes, because an isotonic solution would cause water to leave cells, thereby making them shrink. B. Yes, because an isotonic solution would cause water to enter the cells, thereby making them burst. C. No, it must have been hypertonic because a hypertonic solution would cause water to leave the cells, thereby making them shrink. D. No, it must have been hypotonic because a hypotonic solution would cause water to enter the cells, thereby making them burst.

D. No, it must have been hypotonic because a hypotonic solution would cause water to enter the cells, thereby making them burst.

During transcription in a eukaryote, an RNA Polymerase has reached a sequence in the DNA that is complementary to a stop codon: ATT. At this point what would happen? A. Transcription would stop. RNA-pol II would immediately detach from the DNA and begin the process of translation. B. Transcription would stop. RNA-pol II would remain attached to the DNA. C. Transcription would stop temporarily and the mRNA would detach. Then RNA-pol II would begin the process of transcription again until another stop codon is reached. D. RNA-pol II would transcribe the stop codon and continue transcribing until after the poly(A) signal, when RNA-pol II detaches from the DNA.

D. RNA-pol II would transcribe the stop codon and continue transcribing until after the poly(A) signal, when RNA-pol II detaches from the DNA.

What if a bacterium has a mutant tRNA with anticodon AAA (codon = UUU). The mutation does not allow amino acids to attach to the tRNA. Which of the following may happen in this cell? A. DNA replication could not occur. B. RNA synthesis could not occur. C. All proteins would end just before a phenylalanine. D. Ribosomes could make proteins with phenylalanine if the mRNA included no UUU codons.

D. Ribosomes could make proteins with phenylalanine if the mRNA included no UUU codons.

After a sodium gradient is established, which side of the plasma membrane would you expect to be more positively charged? A. There will be no difference in charge between the extracellular and intracellular sides of the membrane. B. The extracellular side of the membrane will be more negatively charged C. The intracellular side of the membrane will be more positively charged. D. The extracellular side of the membrane will be more positively charged.

D. The extracellular side of the membrane will be more positively charged.

Cancer cells are characterized by increased cell division. Inhibitors of microtubule assembly, colchicine for example, are used for cancer chemotherapy. How does an inhibitor of microtubule assembly affect cancerous cells? A. The inhibitor interferes with energy production, thus stopping motor proteins needed for cell division. B. The inhibition of microtubules interferes with the synthesis of proteins. C. The inhibitors bind the microtubule to the nuclear membrane, stopping cell division. D. The inhibitors prevent the separation of chromosomes, thereby stopping cell division.

D. The inhibitors prevent the separation of chromosomes, thereby stopping cell division.

Compare the two cells shown in this image. Which of the following is correct? A. The right cell has twice as many chromosomes as the left cell, but both cells contain the same amount of DNA. B. The right cell contains twice the number of chromosomes and amount of DNA as the left cell. C. Both cells contain the same number of chromosomes and the same amount of DNA. D. The number of chromosomes in both cells is the same, but the right cell contains twice the amount of DNA as the left cell.

D. The number of chromosomes in both cells is the same, but the right cell contains twice the amount of DNA as the left cell.

Which of the following statements about the relationship between lifespan of a species and DNA repair cannot be supported from the data shown in the graph? A. DNA repair has a significant effect on the life span of a species. B. Naked mole rats have a high NER efficiency, whereas mice have a low NER efficiency. C. The species with long life span enhances its ability to recover after exposure to DNA damage. D. The species with short life span recover from DNA damage faster than the species with long life span.

D. The species with short life span recover from DNA damage faster than the species with long life span.

Scientists discovered that the enhancer associated with hair color has a binding site for a particular transcription factor. One of the binding sites has the sequence CACTAAG and is associated with dark hair, and the other form of the binding site has the nearly identical sequence CGCTAAG. How could these two nearly identical enhancer binding sites lead to different rates of initiating transcription of the regulated gene? A. Since they are so similar, the transcription factor could bind with the same affinity to the two closely related sequences, but the frequency of transcription initiation would be lower for one sequence. B. Since they are so similar, the transcription factor could bind with the same affinity to the two closely related sequences, but the frequency of transcription initiation would be higher for one sequence. C. The transcription factor could bind with different affinities to the two closely related

D. The transcription factor could bind with different affinities to the two closely related sequences, with the sequence promoting stronger binding leading to higher frequencies of transcription initiation.

How do histone deacetylases (HDAC) alter chromatin structure? A. They acetylate histones, making them more negatively charged and condense the chromatin. B. They deacetylate histones, making them more negatively charged, which de-condenses the chromatin. C. They acetylate histones, making them more positively charged and condensing the chromatin. D. They remove acetyl groups from histones, making them more positively charged and condense the chromatin.

D. They remove acetyl groups from histones, making them more positively charged and condense the chromatin.

A mutation occurs in this portion of a chromosome where thymine replaces guanine. What impact do you think this will have on the DNA structure below? A. This will cause the phosphodiester bonds to break, and the DNA will hydrolyze. B. This will cause the DNA secondary structure to denature or unzip. C. This will cause a bulge in the DNA secondary structure. D. This will cause a slight distortion in the DNA secondary structure.

D. This will cause a slight distortion in the DNA secondary structure.

Our DNA is constantly being repaired due to environmental damage, DNA polymerase errors, or chromosome alterations. In humans, xeroderma pigmentosum (XP) is a disorder where individuals are unable to repair DNA damage caused by ultraviolet light. This is a result of __________. A. Mismatch errors B. Telomere shortening C. DNA polymerase proofreading errors D. Thymine dimers

D. Thymine dimers

In a eukaryotic Gene "X", what if a mutation changes the first AUG (for Methionine) in the mRNA to AUA. Of the following, which would be more likely to happen in this cell? A. The mRNA would remain inside the nucleus and no translation would occur. B. Translation would begin normally, and at the same location. C. Translation would NOT occur, because the first start codon AUG has been altered. D. Translation would begin at the second AUG, if there is a second AUG. The protein would be shorter.

D. Translation would begin at the second AUG, if there is a second AUG. The protein would be shorter.

The light-producing genes of V. fischeri are organized in an operon that is under positive control by an activator protein called LuxR. When would you expect the genes of this operon to be transcribed? A. When LuxR expression is silenced by a repressor protein. B. When LuxR expression is under negative control. C. When LuxR is not bound to a DNA regulatory sequence. D. When LuxR is bound to a DNA regulatory sequence.

D. When LuxR is bound to a DNA regulatory sequence.

G proteins are activated when _____. A. They are always active B. a hormone enters the cell and binds to them C. a second messenger binds to them D. a hormone binds to the receptor that they are attached to

D. a hormone binds to the receptor that they are attached to

A series of enzymes catalyze the reaction X→Y→Z→A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. Using this information, substance A functions as a ____________ and substance X functions as a ____________. A. substrate; product B. coenzyme; substrate C. competitive inhibitor; substrate D. allosteric inhibitor; substrate

D. allosteric inhibitor; substrate

Glycosidic linkages are common to ____________, whereas __________ are found in fats (triglycerides). A. proteins; phosphodiester linkages B. DNA; ester linkages C. glycogen; peptide bonds D. carbohydrates; ester linkages

D. carbohydrates; ester linkages

Rubisco binds to CO2 and catalyzes a chemical reaction that fixes CO2 to RuBP. Once this reaction occurs, Rubisco _____. A. has been converted to 3-phosphoglycerate (3PGA) B. is the product of the reaction C. cannot be used again D. is unchanged

D. is unchanged

What amino acid sequence will be generated, based on the following mRNA codon sequence? 5' AUG-UCU-UCG-UUA-UCC-UUG 3' A. met-arg-glu-arg-glu-arg B. met-glu-arg-arg-glu-leu C. met-ser-leu-ser-leu-ser D. met-ser-ser-leu-ser-leu

D. met-ser-ser-leu-ser-leu

Point mutations are referred to as missense, silent, frameshift, or nonsense when they change the protein-coding potential of a gene. What is another group of mutations that may have important consequences for gene expression? A. combinations of missense and silent mutations B. mutations that alter the amino acid sequence of a gene C. mutations that shift the reading frame of a gene D. mutations that exist outside coding sequences in regulatory regions

D. mutations that exist outside coding sequences in regulatory regions

Which of the following is not an extracellular role of carbohydrates? A. protect an insect's internal organs from external trauma B. prevent plant cells from lysing after the plant is watered C. maintain the shape of a fungal spore D. provide energy for muscle movement

D. provide energy for muscle movement

Enzymatic activity can be controlled by _____ whereas when and where the enzyme functions can be regulated by _____. A. the active site; substrate B. time; allosteric molecules C. pH; substrate D. temperature; allosteric molecules

D. temperature; allosteric molecules

In humans, xeroderma pigmentosum (XP) is a disorder of the nucleotide excision repair mechanism. These individuals are unable to repair DNA damage caused by ultraviolet light. Which of the following are the most prominent types of DNA lesions in individuals suffering from xeroderma pigmentosum? A. mismatch errors B. methylation of bases C. telomere shortening D. thymine-thymine dimers

D. thymine-thymine dimers

The codon for serine is 5'-UCG-3'. The coding (non-template) strand of the DNA that encoded it is _____, and the anticodon of the tRNA that recognizes it is _____.

DNA coding strand: 5'- TCG-3 and anticodon: 5'-CGA-3'

Explain the role of ATP in the energy-investment phase. Why is it not necessary for the energy-payoff phase?

Early reactions are endergonic; need ATP coupling to make exergonic. Later reactions are already exergonic.

If you understand gastrulation in a frog embryo, you should be able to describe how the ectoderm comes to completely cover the embryo.

Future ectodermal cells are initially at one pole of the spherical embryo. During gastrulation, they spread out as an expanding sheet that eventually covers the entire embryo as the future endodermal and mesodermal cells move into the interior of the embryo.

According to the diagram below, which substance is experiencing secondary active transport? Na+ Glucose Plasma membrane Molecule A

Glucose (look for substance going from low to high concentration)

Using the metabolic pathway below, predict how inactivating enzyme 2 would affect the concentration of molecules A, B, C, and D relative to what they would be if the pathway was fully functional. A-->B-->C-->D

If enzyme 2 is inactivated, molecules C and D would not be produced because the pathway would be cut off. The concentration of molecule B would increase as it would no longer be converted into molecule C, and the concentration of molecule A would also slightly increase due to the build-up of B.

Compare and contrast the flow of electrons in the chloroplast and mitochondria. Identify the primary electron donors and terminal electron acceptors, and their energy levels.

In mitochondria, electrons begin with high energy (in forms of NADH and FADH2) and eventually go through the electron transport chain. They gradually decrease in energy and are finally accepted by O2 to form H2O. In contrast, H2O is the primary donor of electrons in chloroplasts, which are then excited to higher energy levels due to photon energy and end up in a high-energy electron carrier, converting NADP+ into NADPH.

WE'RE DONE WITH BIO!

LETS GOOOOOOOOOOOOOOO!!!!!

Neurodegenerative diseases such as Alzheimer's often have amyloid deposits due to proteins that have appropriate 1o structure but improper 3-D folding (3o). Explain what may be the most likely cause of amyloid deposits?

Malfunction of the molecular chaperones which are responsible for folding the protein.

Using CRISPR to decrease telomerase activity in cancer cells may be a way to slow tumor growth. Which DNA repair mechanism would be used to accomplish this?

NHEJ (Non-homologous end joining) = gene knockout

According to the diagram below, which substance is experiencing passive transport? Na+ Glucose Plasma membrane Molecule A

Na+ (look for substance going from high to low concentration)

Gerstmann-Sträussler-Scheinker disease (GSS) is a rare inherited disease in humans associated with mutations in the PrPc protein gene that change amino acids within the protein, and make the GSS protein more prone to misfolding and aggregation. When researchers changed six histidines for tyrosines, PrPc lost its ability to bind copper. The structural formula of histidine and tyrosine are shown below. The R-groups highlighted in gray are______. a. Nonpolar for both histidine and tyrosine b. Polar (partial charges can form with hydrogen bonds) for tyrosine and electrically charged/basic for histidine c. Nonpolar for tyrosine due to the ring structure and electrically charged/acidic for histidine d. Electrically charged/basic for histidine and electrically charged/acidic for tyrosine

b. Polar (partial charges can form with hydrogen bonds) for tyrosine and electrically charged/basic for histidine

The ATP made during the fermentation process is generated by ________. a. The electron transport chain b. Substrate-level phosphorylation c. Chemiosmosis d. Oxidative phosphorylation

b. Substrate-level phosphorylation

Canine phosphofructokinase (PFK) deficiency afflicts Springer spaniels, affecting an estimated 10 percent of the breed. Given its critical role in glycolysis, one implication of the genetic defect resulting in PFK deficiency in dogs is ________. a. Early embryonic mortality b. Elevated glucose levels in the dog's blood c. An intolerance for exercise d. A reduced life span

c. An intolerance for exercise

Which of the following correctly matches a component of the cytoskeleton to one of its functions? a. Microtubules help animal cells divide into two b. Actin filaments cause bending of cilia c. Intermediate filaments anchor the nucleus d. Microfilaments move chromosomes

c. Intermediate filaments anchor the nucleus

What are prions? a. Viruses that infect animal cells. b. Viruses that infect bacteria. c. Misfolded, infectious proteins. d. Infectious bacteria.

c. Misfolded, infectious proteins.

The molecule below is ___________ and this is its _________ structure. 5'- A C U A A A U C G A U A U A U A A G G A A -3' a. a protein; 1o b. DNA; 2o c. RNA; 1o d. a ribozyme; 3o

c. RNA; 1o

Once a cell completes mitosis, molecular division triggers must be turned off. What happens to MPF during mitosis? a. It is completely degraded b. It is exported from the cell c. The cyclin component of MPF is degraded d. The Cdk component of MPF is degraded and exported from the cell

c. The cyclin component of MPF is degraded

If one strand of a DNA molecule has the sequence of bases 5'-ATTGCA-3', the other complementary strand would have the sequence _____. a. 5'-TAACGT-3' b. 3'-UAACGU-5' c. 5'-UAACGU-3' d. 5'-TGCAAT-3'

d. 5'-TGCAAT-3'

Reactions that require CO2 take place in ________. a. The light reactions alone b. The Calvin cycle alone c. The C4 cycle alone d. Both the Calvin cycle and the C4 cycle.

d. Both the Calvin cycle and the C4 cycle.

Proteins that interact with DNA often interact with the phosphates that are part of this molecule. Which of the following types of amino acids would you predict to be present in the part of the protein that interacts with the phosphates in DNA? a. Electrically charged/acidic amino acids b. Polar amino acids (partial charges can form with hydrogen bonds) c. Nonpolar amino acids d. Electrically charged/basic amino acids

d. Electrically charged/basic amino acids

Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will most directly affect the ________. a. Splitting of water b. Absorption of light energy by chlorophyll c. Flow of electrons from photosystem II to photosystem I d. Synthesis of ATP

d. Synthesis of ATP

In a cellular protein that resides in the cytosol, where would you expect to find an amino acid like valine? a. on the exterior surface, interacting with water b. in the interior, protected by the sugar-phosphate backbone c. on the interior of the double helix, away from water d. in the interior of the folded polypeptide, away from water

d. in the interior of the folded polypeptide, away from water

The chemical reaction illustrated in the accompanying figure ___. a. links two polymers to form a monomer b. joins two fatty acids together c. is a hydrolysis reaction d. results in a peptide bond

d. results in a peptide bond

Which of the following initiates translation in eukaryotes/prokaryotes? A. Mediator protein assembling activators, general transcription factors, and RNA polymerase at the promoter B. Base pairing of activated methionine-tRNA to AUG of the messenger RNA C. Binding of the smaller ribosomal subunit to Shine-Dalgarno sequence D. The small subunit of the ribosome recognizing and attaching to the 5' cap of mRNA

eukaryotes - The small subunit of the ribosome recognizing and attaching to the 5' cap of mRNA prokaryotes - Binding of the smaller ribosomal subunit to Shine-Dalgarno sequence

The ATP made during fermentation/light reactions is generated by ____.

fermentation - substrate/level phosphorylation light reactions - photophosphorylation

The color of your eyes, skin, and hair is a product of cellular activity. In some animals, pigmentation is dynamic. The distribution of melanosomes in cells is tightly regulated in animals that rapidly change color. Dark-colored cells have melanosomes scattered throughout the cytoplasm while light-colored cells have them aggregated near the nucleus. What if cells use the cytoskeleton and motor proteins to change the distribution of melanosomes? A) Draw and label a simple model of a cell (containing the necessary structures) representing each cell color (2 drawings: dark-colored cells and light-colored cells). B) Under each drawing, describe specifically how cells could use the cytoskeleton and motor proteins to change the distribution of melanosomes.

in textbook chapter review

Explain why many different molecules—including lipids, amino acids, and CO2—end up radiolabeled when cells are fed glucose with radioactive carbons (14C).

Products formed during glucose catabolism are used to make lipids, amino acids. CO2 is a direct product formed during pyruvate processing & Citric Acid Cycle. Examples: Glucose → Pyruvate → Acetyl CoA → Fatty Acids → Phospholipids Glucose → Pyruvate → Acetyl CoA → Citric Acid Cycle → Amino Acid synthesis Glucose → Pyruvate → Acetyl CoA → Citric Acid Cycle → CO2

What if Ras has a GTP analog bound to it that cannot be hydrolyzed, what effect would this have on the cell?

Ras would remain active and continue stimulating the phosphorylation cascade even when no signal molecule is bound to the RTK. This would cause cells to continue dividing, leading to cancer.

Predict what would happen to regulation of the lac operon if the lacI gene were moved 50,000 nucleotides upstream of its normal location. Explain.

Regulation of the lac operon should be normal. The location of the lacI gene isn't important, because the gene produces a protein that diffuses within the cell to the operator.

Compare and contrast (a) substrate-level phosphorylation, (b) oxidative phosphorylation, and (c) photophosphorylation.

Similar: All require enzymes; all produce ATP from ADP Different: - SLP uses an enzyme to transfer a phosphate from a substrate to ADP, whereas OP & PP forms ATP from ADP and Pi. - SLP uses the energy in a phosphorylated substrate to drive the reaction, whereas OP & PP use a proton-motive force (H+ electrochemical gradient) generated by the ETC to supply the energy for ATP synthase to make ATP. - The initial energy source in OP is from NADH/FADH2 (or glucose) oxidation, whereas the initial energy source in PP is light energy. - The number of ATP molecules made in each process: more in OP

Bicoid mRNA is expressed in a gradient in Drosophila embryos. Loss of Bicoid function leads to embryos with two posterior ends. What if researchers injected Bicoid mRNA into the posterior end of an embryo with no Bicoid function, what would be the phenotype of this embryo? Draw it.

Since Bicoid mRNA was injected into the posterior end and the mutant embryo has two posterior ends, the new larva will develop two anterior regions on both ends.

Which categories of amino acid would you expect to find on the surface of a soluble protein and which categories would you expect to find in the interior? What distribution of amino acids would you expect to find in a protein embedded in a lipid bilayer?

Surface of a soluble protein (i.e. antibody) would contain polar and charged amino acids to interact with water and interior of a soluble protein could contain nonpolar, polar and charged amino acids. Surface of a protein embedded in the lipid bilayer (i.e. porin) would contain nonpolar amino acids where it interacts with the phospholipid fatty acid tails and polar and charged amino acids where it interacts with the cytosol or extracellular fluid. The interior would contain polar and charged amino acids needed to transport polar solutes.

Predict the final location of a protein that was experimentally modified to include a nuclear localization signal, an ER signal sequence, and a mannose-6-phosphate tag. Justify your answer by addressing the impact of each signal on its transport.

The ER signal sequence indicates that the protein is synthesized in the lumen of the ER, and since the protein will not be in the cytosol, the NLS will not be expressed. The protein will then move from the ER to the Golgi apparatus for further processing, and since the protein also has the mannose-6-phosphate tag, it will then travel to a lysosome via a vesicle.

Predict the relative concentration of starch in leaves at the start of the day versus the end of the day.

The concentration of starch would be highest at the end of the day and lowest at the start of the day. Starch is made and stored in the chloroplasts of leaves during periods of high photosynthetic activity during the day. At night, it is broken down to make sucrose, which is transported throughout the plant to drive cellular respiration.

Determine if the following reaction is spontaneous or not, addressing both potential energy and entropy. Explain how this obeys the 1st Law of Thermodynamics. CH4 + 2 O2 --> CO2 + 2 H2O

The entropy of the reaction is unchanged as there are an equal number of molecules on the products' and reactants' sides. However, the products side has lower potential energy due to less nonpolar, high potential energy C-H bonds and more polar bonds than the reactants. Therefore, the reaction is spontaneous as ΔH < 0. As this is a balanced equation, it demonstrates the 1st Law of Thermodynamics as no energy is created nor destroyed, it is only converted.

When actively growing cells are treated with Taxol, a chemical isolated from plant cells that prevents microtubule depolymerization, they often are unable to complete the cell cycle. Based on what you have learned about cell-cycle checkpoints, which checkpoint likely causes these cells to arrest? Why?

When treated with Taxol, the cells would arrest in the M phase (which involves mitosis and cytokinesis). Taxol causes the inhibition of microtubule depolymerization, so there would not be complete separation of chromosomes in anaphase (part of M phase), meaning that the cells would then arrest.

Predict how the following conditions would affect the production of O2, ATP, and NADPH and state whether noncyclic or cyclic electron flow would occur in each: a. What if only blue photons hit a chloroplast? b. What if blue and red photons hit a chloroplast, but no NADP+ is available?

a) Blue photons are high-energy photons, and O2, ATP, and NADPH would be formed via noncyclic electron flow. b) Since there is no NADP+ available, no NADPH would be produced and photosynthesis will occur in cyclic electron flow (meaning also no O2).

Some viruses are often associated with cancer. One proposed mechanism is that the virus encodes a protein that [binds Rb]. Based on this fact, which checkpoint is affected? a) G1 b) G2 c) M1 d) M2

a) G1

In general, a signal transmitted via phosphorylation of a series of proteins ________. a. Results in a conformational change to each protein b. Requires binding of a hormone to an intracellular receptor c. Activates a transcription event d. Generates ATP in the process of signal transduction

a. Results in a conformational change to each protein

What if NADH competitive inhibition occurs, what will happen to the levels of succinate and isocitrate in the citric acid cycle shown in the accompanying figure? a. Succinate will decrease, and isocitrate will accumulate b. Both succinate and isocitrate will decrease c. Succinate will accumulate, and isocitrate will decrease d. Both succinate and isocitrate will accumulate

a. Succinate will decrease, and isocitrate will accumulate

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs? a. The pH of the matrix increases b. ATP synthase pumps protons by active transport c. NAD+ is oxidized. d. The cytochromes phosphorylate ADP to form ATP

a. The pH of the matrix increases

When electrons flow along the electron transport chain of thylakoid membranes, which of the following changes occurs? a. The pH of the stroma increases b. ATP synthase pumps protons by active transport c. NADP+ is oxidized. d. The pH of the lumen increases

a. The pH of the stroma increases

Explain how each signal deactivation method turns off the signal? a. GTP hydrolysis b. Phosphatase activity c. Phosphodiesterase activity

a. inactivates the G-protein by converting GTP to GDP which causes a shape change, and stops activation of its downstream target b. removal of phosphate groups from molecules involved in the phosphorylation cascade c. hydrolysis of the second messengers cAMP & cGMP

Prions are unusually resistant to an enzyme called proteinase K which breaks proteins into their monomer building blocks. Which bonds are being broken by the enzymatic action of proteinase K? a. peptide bonds between amino acids b. phosphodiester linkages between nucleotides c. disulfide bonds between amino acids d. peptide bonds between nucleotides

a. peptide bonds between amino acids

Insulin is a peptide hormone secreted by the beta cells of the pancreas, controlling blood glucose levels by signaling the liver, muscle, and fat cells to take in glucose from the blood. According to this information, insulin must contain ___, the beta cells must contain lots of ___, and insulin is transported in the blood via _____.

an ER signal sequence; rough endoplasmic reticulum; exocytosis

Adjacent animal/plants cells communicate by sharing contents of their cytoplasm via ____. A. plasmodesmata B. gap junctions C. desmosomes D. tight junctions

animals - gap junctions plants - plasmodesmata

Reactions that require ATP take place in ______. (also for CO2)

b) the Calvin cycle alone

Which structural formula depicts a ribonucleotide? a. A. b. B. c. C. d. D.

b. B (look for pentose sugar, phosphate group = two O's and an OH, and a nucleotide base)

Lipid-soluble signaling molecules, such as testosterone, cross the membranes of all cells but affect only target cells because ________. a. G-protein-coupled receptors are present only in target cells b. Intracellular receptors are present only in target cells c. Only target cells produce second messengers in response to testosterone d. Only target cells posses the cytosolic enzymes that transduce the testosterone

b. Intracellular receptors are present only in target cells

What can you infer about a high-molecular-weight protein that cannot be transported into the nucleus? a. It is too large b. It lacks a nuclear localization signal (NLS) c. It lacks a mannose-6-phosphate tag d. It lacks an ER signal sequence

b. It lacks a nuclear localization signal (NLS)

When electrons flow along the electron transport chains in the mitochondria/chloroplast, which of the following changes occurs?

mitochondria - pH of the matrix increases chloroplast/thylakoid membranes - pH of the stroma increases

What if the regulatory site in phosphofructokinase (PFK) had a higher affinity for ATP than the active site. Show how the rate would change by drawing a graph of rate of ATP production vs ATP concentration.

normal - start of high and go down as ATP concentration increases changed - will be constantly low (ATP binding to regulatory stopping production)

Mad cow disease is an infectious disease where one misfolded protein causes all other copies of the protein to begin misfolding. This is an example of a disease impacting _______ structure.

tertiary (3°)

In general, a signal transmitted via phosphorylation of a series of proteins results in ____.

the hydrolysis of ATP in the process of signal transduction OR a conformational change to each protein

A solution with a hydrogen ion concentration of 0.0015 M has a pH of ________, and is therefore _________. A. 3.5, acidic B. 2.82, acidic C. 15, basic D. 1 × 10-1.5, basic

B. 2.82, acidic

electrophoresis gel: Assume that both samples A and B are purified functional proteins. An extra band appears in sample B at the same location on the gel as sample A. What might you conclude from this result?

C. Sample B has quaternary structure

In cell signaling pathways, which of the following is most likely to block a secondary messenger system? A. Inhibiting phosphodiesterase activity B. Inhibiting phosphatase activity C. Preventing the exchange of GDP for GTP D. Blocking binding of a steroid hormone, such as estrogen or testosterone.

C. Preventing the exchange of GDP for GTP.

If molecule X is C2H6, what does the above diagram indicate is happening? A. Simple diffusion out of the cell B. Facilitated diffusion out of the cell C. Active transport out of the cell D. Active transport into the cell E. Neither of the above, because molecule X cannot cross the membrane

A. Simple diffusion out of the cell

In class we stated that ribosomal RNA is a type of ribozyme, catalyzing the formation of a peptide bond. Which of the following best describes the tertiary structure of RNA molecules, such as ribozymes?

A single nucleotide strand where multiple "stem and loop" structures begin to interact

Lysozyme, an enzyme found in human saliva, tears, and other secretions, catalyzes the hydrolysis of the β-1,4-glycosidic linkages in peptidoglycan. A) What family of macromolecules does the substrate of this enzyme belong? B) Name two other molecules this enzyme may be able to hydrolyze. C) Predict the effect of this enzyme on bacteria and how it may be involved in human health.

A) carbohydrates B) chitin and cellulose (lactose also acceptable) C) When bacteria contact lysozyme, the peptidoglycan in their cell walls begins to degrade, leading to the death of the bacteria. Lysozyme therefore helps protect humans against bacterial infections.

Normal b-hexosaminidase A (HexA) is a heterodimer, consisting of an a-subunit and a bsubunit. In Tay-Sachs disease, a single amino acid is changed in the a-subunit causing the formation of two mutants. Mutant 1, E482K, has the amino acid E replaced with K at residue number 482 and Mutant 2, G269S, has the amino acid G replaced with S at residue 269. Both mutants are defective in enzymatic activity and exhibit altered folding pathways compared with wild-type a-subunit. Mutant E482K is more severely misfolded than G269S, as observed by its aggregation and inability to associate with the HexA β-subunit. A) What family of macromolecules does b-hexosaminidase A (HexA) belong? B) We discussed levels of structures (1o , 2o , 3o , 4o ) for macromolecules. Based on the information in the prompt alone, what levels of structure are altered in HexA? For each structural level chosen, briefly support your selection with evidence

A) proteins B) Primary structure (1o ): a single amino acid is changed in the a-subunit (any mention of amino acid) Secondary is not altered Tertiary structure (3o ): exhibit altered folding pathways (any mention of folding); aggregation Quaternary (4o ): heterodimer; inability to associate with the HexA β-subunit C) Mutant 1 has a change in charges from a negatively charged acidic amino acid (glutamic acid) to a positively charged basic amino acid (lysine). This could seriously disrupt the ionic bonds which may be formed in the 3o structure. Mutant 2 has a change from a mildly nonpolar H (glycine) to a polar hydroxyl (serine) which may create unintended new hydrogen bonds in the 3o structure, which is not as severe as disrupting ionic bonds.

Put the following steps of DNA replication in chronological order: 1. Single-stranded binding proteins attach to DNA strands. 2.Hydrogen bonds between base pairs of antiparallel strands are broken. 3. Primase binds to the site of origin. 4. DNA polymerase binds to the template strand. 5. An RNA primer is created. A. 2, 1, 3, 5, 4 B. 3, 2, 1, 5, 4 C. 1, 2, 3, 4, 5 D. 3, 1, 2, 4, 5

A. 2, 1, 3, 5, 4

Which molecule becomes reduced in the following chemical reaction? 3-Phosphoglycerate (3PGA) + NADPH → Glyceraldehyde-3-phosphate (G3P) + NADP+ + H+ A. 3PGA B. G3P C. NADP+ D. NADPH

A. 3PGA

How many amino acids are in the protein coded by the following: (some really long strand - just review steps for this lol I ain't writing all that) A. 5 B. 6 C. 7 D. 9

A. 5

Where is the stop codon located in the structure below? A. At the upstream end of the 3' UTR B. At the downstream end of the 5' UTR C. in the DNA just upstream of where transcription starts D. Nowhere in this structure because start codons are not found in proteins

A. At the upstream end of the 3' UTR

Which of the following is not dependent upon hydrogen bonding interactions?

C. Primary structure of a protein

With regards to transcription, what determines the start site and direction of transcription? A. Exons B. Introns C. Promoter D. Start Codon

C. Promoter

What would happen to the function of this chymotrypsin if all other proteins were already broken down into individual amino acids? A. Fewer proteins will be torn apart B. More proteins will be torn apart C. Chymotrypsin will start working on substrates made of carbohydrates D. The bonds that create the tertiary structure of chymotrypsin change

A. Fewer proteins will be torn apart

The graph below shows the rate of product formation in an enzyme-catalyzed reaction as a function of varying substrate concentration, with the concentration of enzyme constant. What is this enzyme was regulated by allosteric activation and the regulatory molecule is left out of the reaction. Which graph would best represent the rate of product formation? A. Graph A only B. Graph B only C. Both graphs D. Neither graphy

A. Graph A only (low rate of reaction only slightly increasing)

electrophoresis gel: What can you conclude about samples, A and B?

A. RNA sequence A is larger and longer than sample B. (didn't travel as far = not as fast = bigger)

In a series of enzyme catalyzed reactions of A + B → C → D → E, we find that increasing the concentration of A & B to 10 M steadily increases the rate of production of E. When A & B are raised to 11 M or more, the rate of increase in C continues to rise, but the rate of production of D & E does not change. What might be occurring? A. Saturation of the enzyme that catalyzes C → D. B. Competitive inhibition of the enzyme that catalyzes A + B → C. C. Feedback allosteric inhibition of E on the enzyme that catalyzes A + B → C. D. Competitive inhibition of the enzyme that catalyzes D → E.

A. Saturation of the enzyme that catalyzes C → D.

The figure below shows the activated and deactivated conformations of the voltage-gated sodium channel. Changes in conformation are based on a regulatory alpha-helix (represented by the gray cylinder on each side of the channel) that slides closer to the cytoplasm in the deactivated state and closer to the exterior of the cell in the activated state. What type of amino acids would you expect to be included in the regulatory alpha helix based on its change in position? A. The helix would contain basic (positively charged) amino acids, such as lysine, arginine, and histidine. B. The helix would contain acidic (negatively charged) amino acids, such as aspartate and glutamate. C. Any type of amino acid could be present in the helix without a change in function. D. The part of the helix that extends into the exterior of the cell would contain hydrophobic amino acids.

A. The helix would contain basic (positively charged) amino acids, such as lysine, arginine, and histidine.

Inhibitors of microtubule assembly, vinblastine for example, are used for cancer chemotherapy. What function of microtubules might this inhibitor block to affect cancer cells? A. The inhibitors prevent the separation of chromosomes, thereby stopping cell division. B. The inhibition of microtubules interferes with the synthesis of proteins. C. The inhibitors disrupts the endomembrane system, stopping cell division. D. The inhibitor interferes with energy production.

A. The inhibitors prevent the separation of chromosomes, thereby stopping cell division.

Which of the following experiments best supports the idea that a transcriptional regulatory sequence can be located in an intron of a gene? A. The intron of a gene is deleted, the gene is introduced into mouse cells, and the mRNA levels are measured. These mRNA levels are compared to a normal gene that is also introduced into mouse cells. The mutated gene shows no mRNA transcription, whereas the normal one is expressed. B. The intron of a gene is deleted, the gene is introduced into mouse cells, and mRNA measurement shows no mRNA expression. C. The gene with all introns intact is introduced into mouse cells and the mRNA levels are measured. The mRNA is transcribed at high levels. D. The exon of a gene is deleted, the gene is introduced into mouse cells, and the mRNA levels are measured. The mRNA levels are compared to a normal gene that is also introduced into mouse cells. The mutated gene shows no mRNA transcription

A. The intron of a gene is deleted, the gene is introduced into mouse cells, and the mRNA levels are measured. These mRNA levels are compared to a normal gene that is also introduced into mouse cells. The mutated gene shows no mRNA transcription, whereas the normal one is expressed.

Why are the genes involved in lactose metabolism in E. coli considered to be an operon? A. They are all controlled by the same promoter. B. They occupy adjacent locations on the E. coli chromosome. C. They have similar function. D. They are all required for normal cell function.

A. They are all controlled by the same promoter.

In eukaryotic gene expression, the step that most prokaryotes do not use is _____. A. post-translational modification B. transcription C. RNA processing D. translation

C. RNA processing

The partial negative charge at one end of a water molecular is attracted to the partial positive charge of another water molecule. What is this attraction called? A. a hydrogen bond B. a covalent bond C. an ionic bond D. A van der Waals interaction

A. a hydrogen bond

A researcher hypothesizes that plant leaf cells express fewer genes in the middle of the night compared to right before the sun rises. She tests her hypothesis by introducing DNase, a nuclease, into the cells at both times. She finds that DNA is cut much more right before the sun rises and that more mRNA is present in the cells at that time. The best interpretation of these results is that _____. A. chromatin remodeling is a crucial component of plant gene regulation overnight B. DNA is inactivated during the night in plants C. plants do not change gene expression between the two night periods D. only post-translational modification contributes to gene regulation between the two night periods

A. chromatin remodeling is a crucial component of plant gene regulation overnight

CAM plants keep stomata closed in the daytime, thus reducing loss of water. They can do this because they ________.

A. fix CO2 into organic acids during the night

Scientists discovered that the difference between blond and dark hair in humans and other mammals comes down in part to a single nucleotide difference in the DNA sequence of an enhancer that lies more than 350,000 base pairs upstream from the coding region of the gene it controls. On average, blonds transcribe this gene less efficiently than people with dark hair. Which of the following statements about this blond/dark hair enhancer is correct? A. the enhancer is associated with a protein during transcription initiation. B. the enhancer is part of the mRNA's 5′ untranslated region. C. the enhancer codes for a large protein. D. the enhancer codes for a small protein.

A. the enhancer is associated with a protein during transcription initiation.

Both proteins and DNA can be denatured and undergo hydrolysis. These processes involve disrupting specific interactions and breaking bonds, which can require enzymes. What would happen to DNA molecules treated with these enzymes?

A. the phosphodiester linkages of the polynucleotide backbone would be broken

In cell signaling, signals are classified as lipid-soluble and lipid insoluble. Testosterone receptors are activated when ____.

A. the signal crosses the membranes of target cells containing the intracellular receptors (Testosterone is lipid soluble)

Using the pH scale on the right, pure water has ____ H+ in solution than tomatoes. A. 1000 times more B. 1000 times less C. 100 times more D. 100 times less

B. 1000 times less

You eat a large plate of non-fat pasta for a late evening snack. Using your knowledge of the central role cellular respiration plays in metabolism and the figure below as a reference, indicate whether: 1. it is possible for the carbon atoms contained in the pasta to end up in the indicated molecules 2. how it is possible or why it is not possible A. Glycogen in muscle tissue: B. The CO2 you exhale: C. The most abundant molecule in your cells' membrane: D. The DNA that codes for an ER resident protein: E. The water made in cellular respiration: F. The O2 used in cellular respiration: G. The ATP synthase in your mitochondrial inner membrane: H. Cellulose making up the cell wall in your intestinal cells:

A.Yes; carbons in the pasta are in the form of a carbohydrate, which is broken down into glucose monomers. Extra glucose monomers are polymerized into glycogen and stored in muscle and liver. B. Yes; glucose is oxidized during glycolysis, pyruvate processing, and the Citric acid cycle. Released as CO2 during pyruvate processing and citric acid cycle. C. Yes; pyruvate oxidation gives rise to Acetyl CoA which is used for fatty acid synthesis, which leads to phospholipid synthesis. D. Yes; intermediates of glycolysis are used for nucleotide synthesis which are monomers for DNA. E. No; water does not contain carbon. F. No; oxygen does not contain carbon. G. Yes; intermediates of the citric acid cycle are used for amino acid synthesis which are monomers for proteins. H. No; humans have no cellulose or cell walls.

Predict what may happen to a protein if a mutation in the anti-codon of tRNA-alanine gene resulted in this tRNA now pairing with the codon for serine. How would this affect the structure and function of this protein?

An alanine would be inserted into the protein sequence in place of a serine sometimes. Alanine is nonpolar and serine is polar so this would certainly alter the structure of this protein, leading to a disruption in function as well.

During transcription, are the RNA and DNA strands parallel or antiparallel? In which direction is the DNA template "read"?

Antiparallel; DNA template strand is read 3' → 5'

A mutation occurs in this portion of a DNA molecule, where an adenine replaces a cytosine. What impact do you think this will have on the DNA structure? A. Adenine is larger than cytosine and will not be able to base pair properly with the guanine on the opposing strand. This will cause the phosphodiester bonds to break, and the DNA will hydrolyze. B. Adenine is larger than cytosine and will not be able to base pair properly with the guanine on the opposing strand. This will cause the DNA to denature or unzip. C. Adenine is larger than cytosine and will not be able to base pair properly with the guanine on the opposing strand. This will cause the DNA to bulge. D. Since adenine is still a nitrogenous base, this mutation will have no impact on the DNA structure.

C. Adenine is larger than cytosine and will not be able to base pair properly with the guanine on the opposing strand. This will cause the DNA to bulge.

A cell undergoing mitosis in a small mammal contains eight chromosomes. During which phases of the cell cycle will this cell contain 16 chromosomes? A. S-phase and G2 B. G1 and G2 C. Anaphase and telophase D. None; this cell will never contain 16 chromosomes.

C. Anaphase and telophase

If NADH competitive inhibition occurs, what will happen to the levels of oxaloacetate and citric acid in the citric acid cycle shown in the accompanying figure to the right?

C. Both oxaloacetate and citric acid will decrease. (ring broken at step 3)

What physical property is associated with the chemical differences between saturated and unsaturated fats? A. C=C bonds normally result in a more compact structure that decreases the spacing between fats and thus makes unsaturated fats less fluid than saturated fats. B. C=C bonds normally form less hydrogen linkages, which increases the spacing between fats and thus make unsaturated fats more fluid than saturated fats. C. C=C bonds normally result in kinks that increase the spacing between fats and thus make unsaturated fats more fluid than saturated fats. D. C=C bonds normally form more hydrogen linkages, which decreases the spacing between fats and thus make unsaturated fats less fluid than saturated fats.

C. C=C bonds normally result in kinks that increase the spacing between fats and thus make unsaturated fats more fluid than saturated fats.

Cells get past cell-cycle checkpoints by _____. A. Cdks working on their own to phosphorylate other proteins B. Cyclins working on their own to phosphorylate other proteins C. Cdks bound to cyclins phosphorylating other proteins D. Cyclins being present at the same level during the entire cell cycle

C. Cdks bound to cyclins phosphorylating other proteins

How is it possible for this blond/dark hair enhancer to regulate transcription of a gene coding region that is so far away? A. Alternative splicing brings the enhancer physically close to the promoter. B. The large activator protein bound to the enhancer stretches from enhancer to promoter like a bridge. C. DNA looping and protein-protein interactions with mediator bring the enhancer physically close to the promoter. D. Post-translational modification of the enhancer allows it to activate gene transcription.

C. DNA looping and protein-protein interactions with mediator bring the enhancer physically close to the promoter.

This table gives the results of assays of percentages of bases from nucleic acids isolated from different sources. The nucleic acid from source 3 is ______ and _____. A. DNA; double stranded B. RNA; double stranded C. DNA; single stranded D. RNA; single stranded

C. DNA; single stranded (has T instead of U, complementary base pairs don't match up so single stranded)

Which of the following has the greatest potential as a cancer treatment? A. Find a way to switch off the gene for making telomerase in all cells in embryos, so that they never develop cancer B. Find a way to switch on the gene for making telomerase in normal cells, so that the normal cells would soon outnumber the cancer cells C. Find a way to switch off the gene for making telomerase in cancer cells, since the cells would stop dividing when the telomeres were gone D. Find a way to switch on the gene for making telomerase in cancer cells, since they will be unable to divide if their telomeres are too long

C. Find a way to switch off the gene for making telomerase in cancer cells, since the cells would stop dividing when the telomeres were gone

In PCR (polymerase chain reaction), ______ is responsible for separating the strands of the double helix and ______ is responsible for making the new DNA daughter strands, whereas during DNA replication in bacteria, ______ is responsible for separating the strands of the double helix and ______ is responsible for making the new DNA daughter strands. A. helicase; DNA Pol; helicase; DNA Pol B. heat; heat resistant DNA Pol; helicase; heat resistant DNA Pol C. Heat; heat resistant DNA Pol; helicase; DNA Pol D. Heat; helicase; primase; ligase

C. Heat; heat resistant DNA Pol; helicase; DNA Pol

Read the following: I. "We tested the hypothesis that the level of vitamin D in blood serum correlates to the expansion of endothelium-dependent blood vessels." II. "We tested the hypothesis that PINK1 and Parkin promote mitochondrial loss by producing targeted destruction of core proteins of mitochondrial development."

C. I is a prediction, but II is a hypothesis

You have isolated a previously unstudied protein, identified its complete structure in detail, and determined that it catalyzes the breakdown of a large substrate. You notice it has one large binding site containing an amino acid that is usually phosphorylated. What do these findings tell you about the mechanism of this protein?

C. It is probably an enzyme that works through competitive inhibition

Why might a point mutation in DNA make a difference in the level of a protein's activity? A. It might exchange one stop codon for another stop codon. B. It might delay the rate of DNA replication. C. It might substitute a different amino acid in the active site. D. It might substitute the N-terminus of the polypeptide for the C-terminus.

C. It might substitute a different amino acid in the active site.

Which of the following would halt glycolysis: A. Lack of O2 B. Lack of CO2 C. Lack of NAD+ D. Both A and C

C. Lack of NAD+

What would be the consequence(s) for DNA synthesis if DNA ligase were defective? A. Leading strand synthesis would be mostly incomplete; lagging strand synthesis would be unaffected B. Both leading and lagging strand synthesis would be mostly incomplete C. Lagging strand synthesis would be incomplete; leading strand synthesis would be largely unaffected D. Both leading and lagging strand synthesis would be unaffected

C. Lagging strand synthesis would be incomplete; leading strand synthesis would be largely unaffected

Aquaporins are proteins embedded in the plasma membrane that allow water molecules to move between the extracellular matrix and the intracellular space. Based on its function and location, describe the key features of the protein's shape and the chemical characteristics of its amino acids. A. The protein must form an amphipathic carrier protein in the plasma membrane that allows water to enter and exit the cell down its concentration gradient. B. The protein must form an amphipathic pump in the plasma membrane that allows water to enter and exit the cell against its concentration gradient. C. The protein must form an amphipathic channel in the plasma membrane that allows water to enter and exit the cell down its concentration gradient. D. The protein must form an amphipathic pump in the plasma membrane that binds water molecules and transports them across the plasma membrane down its concentration gradient.

C. The protein must form an amphipathic channel in the plasma membrane that allows water to enter and exit the cell down its concentration gradient.

Predict what would happen if the lac repressor were altered so it could not release lactose once lactose was bound to it. A. The repressor could bind to DNA only when cells were grown with glucose. B. The repressor could bind to DNA only when cells were grown without glucose. C. The repressor could not bind DNA. D. The repressor would always be bound to DNA.

C. The repressor could not bind DNA.

Identify the lagging strand during DNA replication in the figure below. A. [a] B. [b] C. [c] D. [d]

C. [c] (look for ligase, okazaki fragments)

The molecule to the right, which is frequently found in the stomach, is best categorized as a __ having a(n) ___ bond/linkage. A. lipid; ester B. protein; peptide C. carbohydrate; glycosidic D. lipid; phosphodiester E. None of the above

C. carbohydrate; glycosidic

The amino acid residues at the active site are highly acidic. In designing a drug that would bind to the active site and jam it, researchers should use a molecule that is ______. A. hydrophobic B. polar C. charged D. acidic

C. charged (if site is hydrophobic --> hydrophobic molecule)

You have a planar bilayer with equal amounts of saturated and unsaturated phospholipids. After recording the degree of permeability of this membrane to glucose (there was some permeability), you increase the proportion of saturated phospholipids in the bilayer. This bilayer ______________. A. has changed, but glucose permeability has not B. is more permeable to glucose now C. is less permeable to glucose now D. is less permeable to glucose but more permeable to Na+ ions now

C. is less permeable to glucose now

In the follow-up work to the experiment shown in Figure 19.6, the researchers used a technique that allowed them to see if two DNA sequences are in close physical proximity (association). They applied this method to examine how often an enhancer and the core promoter of the Hnf4a regulatory gene were near each other. A logical prediction is that compared with rats born to mothers fed a healthy diet, the Hnf4a gene in rats born to mothers fed a protein-poor diet would: A. show no difference in how often the promoter and enhancer associated. B. never show any promoter-enhancer association. C. show a lower frequency of promoter-enhancer association. D. show a higher frequency of promoter-enhancer association.

C. show a lower frequency of promoter-enhancer association.

One general common characteristic of the most serious cancers might be _____. A. the ability of defective cells to drain surrounding cells or tissues of nutrients B. the speed at which defective cells divide C. the ability of defective cells to relocate to other tissues D. the location of the cancer

C. the ability of defective cells to relocate to other tissues

Chicken embryos express both Hoxc6 and Hoxc8 in regions where ribs form, but only Hoxc6 in regions where forelimbs form. The fossilized jawbone of a new species of animal was found, and enough DNA was extracted to discover that it had both Hoxc8 and Hoxc6 genes. What can we tell about ribs and forelimbs in this new species?

Cannot tell based on presence of genes. Need information about gene expression in these areas. Unmutated sonic hedgehog gene is present in snakes, but they have no limbs because gene is not expressed.

Scientists experimentally modified the kinesin gene so that it would contain both an NLS and a mannose-6-phosphate tag. What is the normal location of kinesin and its possible new location, respectively? A. Cytosol; Lysosome B. Lysosome; Nucleus C. Nucleus; Lysosome D. Cytosol; Nucleus

D. Cytosol; Nucleus

The membrane protein labeled "A" in the image on the right is carrier protein GLUT-1. What might you expect about the movement of Na+ and/or glucose across the cell membrane?

D. Glucose would likely move from the outside of the cell to the inside.

Which of the following would halt the light capturing reactions in photosynthesis? A. Lack of O2 B. Lack of CO2 C. Lack of H2O D. Lack of Ferredoxin

D. Lack of Ferredoxin

LuxR is allosterically regulated by the signaling inducer molecule secreted by V. fischeri. What does this statement mean? A. LuxR is regulated by its active site breaking down the signaling inducer molecule. B. LuxR is regulated by its active site catalyzing formation of the signaling inducer molecule. C. LuxR is regulated by a change in shape; only the shape without the inducer allows LuxR to bind a DNA regulatory sequence. D. LuxR is regulated by a change in shape; only the shape with the inducer allows LuxR to bind a DNA regulatory sequence.

D. LuxR is regulated by a change in shape; only the shape with the inducer allows LuxR to bind a DNA regulatory sequence.

Compare and contrast (2 each) the three cytoskeletal motor proteins and provide a distinct cellular role for each.

Compare: all require ATP; all made of amino acids Contrast: myosin walks on actin to + end, kinesin walks on microtubules to + end, dynein walks on microtubules to - end; myosin cause muscle contraction, kinesin carries vesicles, dynein moves flagella.

What if cyanide (C=N- ) blocks complex IV in the ETC. Write a hypothesis for what happens to the ETC when complex IV stops working. Explain why cyanide poisoning in humans is fatal.

Cyanide-blocking complex IV in ETC would mean that the electrons wouldn't be transported to the final electron acceptor (O2), greatly inhibiting cellular respiration as a whole. ATP production would drop dramatically and cells would no longer be able to have the energy resources to perform vital functions, eventually leading to cell death. Therefore, cyanide poisoning would be fatal as it would prevent energy production and lead to eventual death in cells impacted by it.

Which of the following statements describe mutations? 1. Point mutations can occur in any DNA sequence. 2. Frameshift mutations can occur in any DNA sequence. 3. Neutral mutations depend on the degeneracy of the genetic code. 4. Deleterious mutations occur only in protein-coding sequences of DNA. A. 1, 2, 3, & 4 B. 1, 2, & 4 C. 1 & 2 D. 1 only

D. 1 only

Which of the following statements about mutations is true? 1. Point mutations only occur in the protein-coding part of a gene. 2. Frameshift mutations only occur in the protein-coding region of a gene. 3. Silent mutations change the primary structure of the protein. 4. Harmful point mutations occur only in protein-coding sequences of DNA A. 1, 2, and 4 B. 1 and 3 C. 2 and 4 D. 2 only

D. 2 only

Given the double-stranded DNA shown below, RNA is synthesized in the ____________ direction by RNA polymerase using _________________. DNA template strand 5' ________ 3' DNA nontemplate strand 3' ________ 5' A. 3' → 5', the nontemplate DNA strand B. 5' → 3', the nontemplate DNA strand C. 3' → 5', the template DNA strand D. 5' → 3', the template DNA strand

D. 5' → 3', the template DNA strand

If the sequence in the coding strand of DNA for a particular amino acid is 5'-GAT-3', then the anticodon on the corresponding tRNA would be ________.

D. 5'-AUC-3'

Membrane protein B in the diagram below is the pore-like channel protein, aquaporin. Where would you expect to find the amino acids alanine and valine?

D. Both would be in the exterior of the channel protein interacting with the phospholipid tails.

How is the aging process linked to telomeres? A. When a person ages, they begin to get larger and larger telomeres B. There is only a link between the aging process and telomeres in naked mole rats, but not in humans C. When telomeres get too long, a signal is sent to the gene to stop the production of all proteins D. Cells with short telomeres can no longer divide, so damaged tissues cannot be repaired

D. Cells with short telomeres can no longer divide, so damaged tissues cannot be repaired

Identify the type of mutation in SLC24A5*2? A. Silent mutation B. Nonsense mutation C. Frameshift mutation D. Missense mutation

D. Missense mutation

An investigator exposes chloroplasts to 700-nm photons and observes low O2 production, but high ATP production. What is a plausible explanation for this observation?

Photosystem II is not splitting water, and the ATP is being produced by cycling electrons via photosystem I.

If a cell receives a vesicle by endocytosis containing macromolecules to be digested, explain where it is going and how it gets there?

Plasma membrane pinches in to form a vesicle containing macromolecules to be digested. Dynein transports vesicle to lysosome by walking on microtubules towards the minus (-) end.

State when you would first be able to point out the future posterior and dorsal regions of a frog embryo and explain what clues you would use to identify these regions.

The future posterior and dorsal regions could be identified as the blastopore forms and cells begin folding into the embryo. The blastopore marks the future posterior region of the embryo, and cells that are the first to be folded into the embryo mark the future dorsal side.

How do the alpha and beta forms of glucose differ?

Their ring structures differ in the location of a hydroxyl group

New drugs are being developed that decrease DNA methylation and prevent the removal of acetyl groups from histone proteins. Explain how these drugs could affect gene expression to help kill tumor cells.

These drugs will keep the histone proteins and the DNA methylation patterns in the open chromosomal configuration so that transcription is feasible. If a gene is silenced, these drugs could reverse the epigenetic configuration to re-express the gene.

In a bacterium, there is a mutation in the gene for the repressor protein of the lac operon. The mutation has changed a codon in the mRNA from UCU to UCC. When lactose is present, how would this mutation affect the function of the lac operon?

This is a silent mutation so the repressor should function normally. When lactose is present, it will bind to the repressor, removing it from the operator and allowing transcription of the lac operon.

Which statement is true of this reaction? CO2 + 2 H2O --> CH4 + 2 O2

This is an endergonic reaction where carbon dioxide carbons are reduced to methane.

The chemical EDTA binds with high affinity to Ca2+ ions. What if you added EDTA to a cell culture, what effect would this have on cell signaling.

This will block signal transduction and amplification when Ca2+ ions are produced as second messengers.

Compare and contrast transcription initiation in bacteria and eukaryotes.

Transcription begins in the cytoplasm for bacteria whereas it begins in the nucleus for eukaryotes. Also, the mRNA in eukaryotes requires further processing before translation that mRNA in bacteria doesn't go through. This can include a 5' cap being added, the splicing of introns, and the addition of a poly(A) tail.

Draw a simple representation of a plasma membrane. Then, for each of the following membrane activities, (1) add a clearly-labeled drawing of the process to your membrane (include any proteins, other molecules involved, symbols, etc.), (2) indicate whether ATP is required or not, and (3) indicate the specific type of transport. (2 pts) movement of water into and out of a cell (hint: don't forget about aquaporins) (1 pt) movement of carbon dioxide into and out of a cell (2 pts) movement of glucose molecules into a cell from the extracellular fluid, which contains a higher concentration of glucose than the concentration inside the cell

a) Show water molecules moving from high to low concentration directly across the lipid bilayer, but moving relatively slowly (by a wavy or thin arrow; or show at equilibrium with bidirectional arrow), and also show them moving more rapidly through aquaporin (protein shape should span membrane and have a channel). No ATP required. Osmosis. (2 pts) b) Show carbon dioxide molecules moving from high to low concentration directly across the lipid bilayer (or show at equilibrium with bidirectional arrow). No ATP required. Diffusion. (1 pts) c) Show glucose moving from high to low concentration through the carrier protein GLUT1, which changes shape upon binding glucose, allowing glucose to enter the cell. No ATP required. Facilated diffusion. (2 pts)

What wavelength of light in the accompanying figure is most effective in driving photosynthesis? a. 420 mm b. 475 mm c. 575 mm d. 625 mm

a. 420 mm

Compare and contrast the flow of electrons in the chloroplast and the mitochondria. a. Draw a general flow chart of the two processes. (3 pts) b. Specify the primary electron donors and indicate if the electrons are at high energy or low energy for each process. (1 pt) c. Specify the terminal electron acceptors and indicate if the final electrons are at high or low energy for each process. (1 pt)

a. Chloroplast: H2O → PS2 → ETC (generates H+ gradient) → PS1 → NADP+ → NADPH (1.5) Mitochondria: NADH/FADH2 → ETC (generates proton motive force) → O2 → H2O (1.5) b. Chloroplast: H2O = primary electron donor, electrons are at low energy; Mitochondria: NADH/FADH2 = primary electron donors, electrons are at high energy c. Chloroplast: NADP+ = terminal electron acceptor, electrons are at high energy; Mitochondria: O2 = terminal electron acceptor, electrons are at low energy

What effect might too much HAT or HDAC have on: a. expression of E2F and the cell cycle? b. expression of Rb and the cell cycle?

a. E2F is a proto-oncogene. Too much HAT will lead to increase transcription, making it an oncogene, leading to cancer. Too much HDAC, opposite effect, less transcription, no cell growth. b. RB is a tumor suppressor. Too much HAT will lead to increase transcription, resulting in G1 arrest and apoptosis. Too much HDAC, opposite effect, less transcription, resulting in cancer.

CAM plants keep stomata closed in the daytime, thus reducing loss of water. They can do this because they ________. a. Fix CO2 into organic acids during the night b. Fix CO2 into sugars in the bundle-sheath cells c. Fix CO2 into pyruvate in the mesophyll cells d. Use the enzyme PEP carboxylase, which outcompetes Rubisco for CO2 in the bundle sheath cells.

a. Fix CO2 into organic acids during the night

Analyze the flow of electrons in chloroplasts. a. Draw a flowchart showing the flow of electrons. b. What are the primary electron donors? c. What are the terminal electron acceptors? d. Are the final electrons at a high energy or low energy state?

a. H2O → PSII → Pheophytin → ETS (PQ → Cyt complex → PC) → PSI → Ferredoxin → NADP+ → NADPH b. Primary electron donor: H2O c. Terminal electron acceptor: NADP+ d. Final electrons at high energy state

PrPc has more α-helices than the infectious prion protein. What type of bond is directly involved in the formation of an α-helix? a. Hydrogen bonds between amino acid residues b. Peptide bonds between amino acid residues c. Van der Waals interactions between nonpolar residues d. Disulfide bonds that form between cysteine residues

a. Hydrogen bonds between amino acid residues

What is the role of PEP carboxylase in C4 and CAM plants? a. It fixes CO2 into an organic acid. b. It produces ATP for the Calvin cycle. c. It replaces Rubisco in the Calvin cycle. d. It releases CO2 from organic acids

a. It fixes CO2 into an organic acid.

Data show that copper binding stabilizes the structure of PrPc. In 2019, researchers hypothesized that copper binding plays a role in PrPc's ability to promote the growth of neurons. To test this hypothesis, they disrupted copper-binding sites on PrPc, by changing histidines to tyrosines (PrP-H→Y). Neurons were isolated from mouse brains and cultured in the lab in a physiological buffer (PBS, mock) or in the presence of wild-type (normal) PrPc in PBS, or the mutant PrP-H→Y in PBS. The growth of neurites (projections from the neuron cell body) was measured in microns (Max growth, µm) by microscopy in replicate samples. A graph of the results is shown below (standard error bars indicate the uncertainty in the mean). A statistical test was performed to determine whether there was a statistically significant difference between the groups. a. What are the results of this experiment? (1 pt) b. What can you conclude fr

a. Neurites grown in the presence of PrPc grew on average ~11.5 μm, compared with ~4 μm for neurites grown in the presence of the mock solution and only ~3 μm for neurites grown in the presence of PrP‐H→Y. b. The results suggest that copper‐binding by PrPc is required for neurite growth and that the difference between histidine (being electrically charged basic) and tyrosine (being uncharged polar) might lead to a disruption of copper‐binding. When comparing PrPc to the mock trial and PrP‐H→Y, the error bars are nonoverlapping, suggesting a difference, and the four asterisks indicate a P value that is highly significant (P<0.0001), confirming that there is a statistically significant difference between PrPc and mock, and PrPc and PrP‐H→Y. When comparing PrP‐H→Y to mock trial, the error bars overlap, suggesting there is not a difference. The absence of asterisks confirm that there is no statistically significant difference between PrP‐H→Y and mock. c. The "mock" treatment served as a "negative" control. The mock group included only PBS, the buffer that acted as the solvent for the proteins (PrPc and PrP‐H→Y). Measuring neurite growth in the presence of PBS confirmed that buffer alone did not promote neurite growth. Stimulation of neurite growth was dependent on the presence of the wild‐type protein.

What if the following condition existed in a cell, could it lead to uncontrolled cell growth resulting in cancer? Justify your response. a. Overexpression of MPF activity b. Rb being underproduced c. Overproduction of BRCA1 d. Ras with a nonhydrolyzable GTP e. Nonfunctional E2F f. Nonfunctional phosphatase

a. No; MPF activity must decrease in order for cells to proceed thru mitosis (anaphase to telophase). b. Yes; underproduced Rb cannot control E2F expression, therefore E2F would drive cell into S-phase. c. No; BRCA1 is tumor suppressor, halting cell in G1. d. Yes; can't turn off phosphorylation cascade to stop signaling e. No; E2F needed to drive cell into S-phase f. No; can't activate G1 cyclin-Cdk; Yes; can't turn off phosphorylation cascade