(Bio 3310) Final Exam Review
The gene for a hormone necessary for insect development contains binding sites for three gene regulatory proteins called A, B, and C proteins. A and B cannot bind simultaneously because the binding sites for A and B overlap. You make mutations in the binding sites for each of the proteins and measure hormone production in cells that contain equal amounts of the A, B, and C proteins. The results of your studies are summarized in the figure and table below. Complete the statement with the answer that is consistent with the results shown in the table. Binding site Hormone production A+ B+ C+ Off A- B+ C+ Off A+ B- C+ Off A+ B+ C- Low Level A- B- C+ Off A+ B- C- Low Level A- B+ C- High Level A- B- C- Off 1. A binds to its operator ______ tightly than B binds to its operator. A. More B. Less 2. A is a _______ activator of transcription than B A. Stronger B. Weaker 3. C is able to prevent activation by _____ A. A only B. B only C. Both A and B
1. A. more 2. B. weaker 3. C. both A and B
Some genes are more highly conserved then others. Pick the more highly conserved genes from each pair. 1. Genes involved in sexual reproduction (A) vs genes involved in translation (B) A. a B. b 2. Genes involved in amino acid synthesis (A) vs genes involved development (B) A. a B. b
1. B 2. A
You have discovered an operon in a bacterium that is only turned on when trehalose (a disaccharide) is present and glucose is absent. You have also isolated three mutants which have changes in the upstream regulatory sequences of the operon and whose behavior is summarized below. You hypothesize that there are two gene regulatory sites in the upstream regulatory sequence, A and B, which are affected by the mutations. + indicates a normal site, and - indicates a mutant site that no longer binds its gene regulatory protein. Glucose Trehalose Glucose + Trehalose normal (A+ B+) OFF ON OFF mutant 1 (A- B+) OFF ON ON mutant 2 (A+ B-) OFF OFF OFF mutant 3 OFF OFF OFF 1. Given that mutant 1 has sites A-B+, the gene regulatory protein that binds to site A is____ that also binds ______. A. a repressor, trehalose B. a repressor, glucose C. an activator, trehalose D. an activator, glucose 2. The gene regulatory protein that binds to site B is ____ that also binds______. A. a repressor, trehalose B. a repressor, glucose C. an activator, trehalose D. an activator, glucose 3. What is the "genotype" of mutant 3? A. (A+B+) B. (A-B+) C. (A-B-) D. either B or C
1. B. a repressor, glucose 2. C. an activator, trehalose 3. D. either B or C
What are the 3 basic tenets of cell theory as proposed by Schleiden, Schwann, and Virchow?
1. all things are made of cells 2. cells come from pre-existing cells 3. cells are the basic unit of life
Explain how a nerve cell's action potential leads to contraction of muscle sarcomeres.
A nerve cell causes a shock which causes the ion channels of a cell to open allowing more Ca2+ in which trigger the reaction that cause the myosin heads to look along the actin.
The F0 base of ATP synthase contains a ring of 12 subunits while the F1 head has 5 different protein subunits in the ratios 3:3:1:1:1. It takes ________ protons for the motor to make one complete revolution, or ________ protons to make one ATP. A. 12, 4 B. 12,2 C. 4, 4 D. 6, 2
A. 12, 4
Which of the following are examples of isotopes? A. 14C and 12C B. valine and alanine C. cytosine and guanine D. D-glucose and L-glucose
A. 14C and 12C
The Na+/K+ ATPase is responsible for maintaining the gradients of these ions across the cell membrane (and helping establish the membrane potential). It does so by pumping; A. 3Na+ molecules out of the cell for each 2K+ molecules brought in B. 2Na+ molecules out of the cell for each 3K+ molecules brought in C. 2K+ molecules out of the cell for each 3Na+ molecules brought in D. The Na+/K+ ATPase is not a pump, it it an ion channel
A. 3Na+ molecules out of the cell for each 2K+ molecules brought in
You want to amplify the DNA between the two stretches of sequence shown below. Of the listed primer pairs, choose the correct pair that will allow you to amplify the DNA by PCR. 5'-CTGGACGAAA----TGTAATGGTT-3' 3'-GACCTGCTTT----ACATTACCAA-5' a. 5'-CTGGACGAAA-3' and 5'-TGTAATGGTT-3' b. 5'-CTGGACGAAA-3' and 5'-AACCATTACA-3' c. 5'-TTTCGTCCAG-3' and 5'-TGTAATGGTT-3' d. 5'-GACCTGCTTT-3' and 5'-ACATTACCAA-3'
A. 5'-CTGGACGAAA-3' and 5'-TGTAATGGTT-3'
What is the source of free energy (delta G) for moving protons out of the mitochondrial matrix against their concentration gradients. A. ATP B. the redox reactions of the electron transport chain C. glycolysis D. creatine phosphate
A. ATP
Please describe the mechanism of action of THREE of the following inhibitors of nerve transmission (please be specific). A. Bo-Tox B. Nerve gas C. Novocaine D. Serotonin reuptake inhibitor E. a-bungarotoxin
A. Bo-Tox inhibits neurotransmitter release and blocks the fusion of neurosecretory vesicle the plasma membrane. Muscles cannot be stimulated (eliminates some facial wrinkles) B. Nerve gas is an irreversible inhibitor acetylcholinesterase. Acetylcholine accumulates keeping the nerve on and this lead to rigor and death. C. Novocaine is a local anesthetic that blocks Na+ ion channels. Neurons cannot generate action potential and that is why a person cannot feel pain D. Serotonin reuptake inhibitor an example is Prozac. When serotonin levels rise it positively affects mood. When people stop taking the inhibitor the system is primed to pull in serotonin but when the inhibitor is no longer present serotonin levels drop dramatically.
Glycolysis has to "prime" the substrate glucose before it can subsequently extract energy from the pathway. What is the compound it uses to do this? A. NADH B. NAD+ C. GTP D. ATP
A. NADH
Transcription of bacteria differs from transcription in eukaryotic cell because A. RNA polymerase (along with its sigma subunit) can initiate transcription on its own B. RNA polymerase (along with its sigma subunit) requires the general transcription factors to assemble at the promoter before polymerase can begin transcription C. The sigma subunit must associate with the appropriate type of RNA polymerase to produce mRNAs D. bacterial RNA polymerase must be methylated at its C- terminal tail
A. RNA polymerase (along with its sigma subunit) can initiate transcription on its own
Acetylcholine acts as a G-protein-linked receptor on heart muscle so makes the heart move slowly by the effect of the G-protein on a K+ ion channel, as shown in Figure Q16-13. Which one of the following would enhance this effect of acetylation? A. a high concentration of a non-hydrolyzable analog of GTP B. mutations in the acetylcholine receptor that weaken the interaction between the receptor and acetylcholine C. mutations in the acetylcholine receptor that weaken the interaction between the receptor and the G-protein D. mutations in the G-protein beta subunit that weaken the interaction between beta gamma and the K+ channel
A. a high concentration of a non-hydrolyzable analog of GTP
Which of the following is NOT a basic property of some cells? A. all cells have mitochondria B. all cells have a way to express genetic information C. all cells are capable of reproduction D. all cells respond to their environments
A. all cells have mitochondria
Eukaryotic plant cells primarily use the glycolytic pathway in opposite directions in the cytosol and chloroplasts, hence the pathway is: A. amphibolic B. anabolic C. catabolic
A. amphibolic
Membrane lipids are _________ molecules because one end of the molecule is __________ while the other end is ________. A. amphipathic/ hydrophobic/ hydrophilic B. amphibolic/ large/ small C. water soluble/ hydrophilic/ hydrophilic D. water soluble/ hydrophobic/ hydrophobic
A. amphipathic/ hydrophobic/ hydrophilic
The enzyme adenylyl cyclase makes the second messenger: A. cAMP B. cGMP C. ATP D. Ca++
A. cAMP
To determine the most functionally important regions of the human genome (what makes us unique), which species would be more useful for comparison? A. chimpanzee (diverged from humans 5 million years ago) B. gorilla (diverged from humans 10 million years ago) C. orangutan (diverged from humans 30 million years ago)
A. chimpanzee (diverged from humans 5 million years ago)
Membranes are enlarged by the insertion of new phospholipids into one side of the membrane. Which side? A. cytoplasmic B. noncytoplasmic
A. cytoplasmic
Any reaction A <---> B can proceed left to right when: A. delta G is negative B. delta G0' is negative C. [A]=[B] D. delta G=delta G0' E. all of the above
A. delta G is negative
Several members of the same family were diagnosed with the same unusual cancer when they were quite young. Which one of the following is the most likely explanation for this phenomenon? Possibly, the individuals with cancer A. have inherited a cancer-causing gene that was mutated in an ancestor's somatic cells B. inherited a mutation in a gene required for DNA synthesis C. inherited a mutation in a gene required for mismatch repair D. inherited a mutation in a gene required for the synthesis of purine nucleotides E. independently accumulated multiple random mutations over a period of years leading to cancer
A. have inherited a cancer-causing gene that was mutated in an ancestor's somatic cells
What advantage does a light microscope have over an electron microscope for the study of cells? A. it allows one to see and pick out individual human cells from a cell culture in order to grow new cultures from them B. it allows one to visualize organelles inside a cell C. it allows one to look at cells stained with chemicals D. it allows one to see ribosomes
A. it allows one to see and pick out individual human cells from a cell culture in order to grow new cultures from them
What is the role of the nuclear localization sequence in a nuclear protein? A. it binds a transport protein that directs the complex to the nucleus B. it is a hydrophobic sequence that enables the protein to enter the nuclear membranes C. it aids protein unfolding in order for the protein to thread through nuclear pores D. it prevents the protein diffusing out of the nucleus via nuclear pores
A. it binds a transport protein that directs the complex to the nucleus
Which of the following is NOT true of the nulcear membrane: A. it consists of the same proteins and lipids as other cellular membranes B. it is composed of a pair of membranes C. it studded with pores D. it functions to separate the genetic material from cytoplasm
A. it consists of the same proteins and lipids as other cellular membranes
Which of the following is NOT true of the enzyme ribulose bis-phosphate carboxylase (RUBISCO): A. it is responsible for photorespiration when O2 rather than CO2 is added to ribulose bis-phosphate B. it is found in the stroma of the chloroplast C. it "fixes" CO2 to phosphoenolpyruvate to make oxalacetate D. it is the most abundant protein on earth
A. it is responsible for photorespiration when O2 rather than CO2 is added to ribulose bis-phosphate
Production of ATP in glycolysis is referred to as: A. substrate-level phosphorylation B. oxidative phosphorylation
A. substrate-level phosphorylation
Which of the following statements about chloroplasts is FALSE? A. the thylakoid membrane is permeable to protons B. the thylakoid membrane contains the photosynthetic electron transport components C. protons are pumped from the stroma into the thylakoid space D. ATP is synthesized in the stroma E. chloroplasts divide to form new chloroplasts
A. the thylakoid membrane is permeable to protons
If you add an N-terminal sequence to a soluble cytoplasmic protein it will be directed to the _________ and it will ultimately end up ___________. A. to the ER, in the lysosome B. to the ER, secreted from the cell C. to the ER, staying in the Golgi D. cytoplasm, in the cytoplasm
A. to the ER, in the lysosome
Biological macromolcules are put together by condensation reactions that polymerize building blocks. A. true B. false
A. true
Each respiratory enzyme complex in the ETC has a greater affinity for electrons than its predecessors, so that electrons pass sequentially from one complex to another until they are finally transferred to oxygen, which has the greatest electron affinity. A. true B. false
A. true
The most important contribution of the citric acid cycle to energy metabolism is the extraction of high energy electrons during the oxidation of acetyl CoA to CO2. A. true B. false
A. true
The strength of one the chemical bonds below is dramatically decreased in the presence of water: A. van der waals interaction B. covalent bond C. ionic bond D. hydrophobic interaction
A. van der waals interaction
When the neurotransmitter acetylcholine is applied to skeletal muscle cells it activates the acetylchloline receptor that is a calcium ion channel causing the muscle cells to contract. In other words, acetylcholine is an agonist for the receptor. A similar molecule, succinylcholine, has been demonstrated to bind the same acetylcholine receptor on skeletal muscle cells and is sometimes used by surgeons as a muscle relaxant. Why does succinylcholine cause muscle relaxation instead of contraction, as acetylcholine does? In other words, what would you call succinylcholine?
Antagonist
The bold sequences (TTGACA and TATATT) represent what? A. TATA boxes recognized by RNAP II B. -35 and -10 boxes recognized by the sigma factor of RNAP C. binding sites for general transcription factors D. binding sites for the small subunit of the ribosome
B. -35 and -10 boxes recognized by the sigma factor of RNAP
What is the typical diameter of a eukaryotic cell? A. 2 micrometers B. 20 micrometers C. 2 millimeters D. 20 millimeters
B. 20 micrometers
In the replication of DNA the polymerase adds nucleotides to the ______ end of a primer. A. 2' B. 3' C. 5'
B. 3'
A nucleotide sequence is said to be palindromic if it is complementary to itself. Which of the following sequences is palindromic (self-complementary)? A. 5'-AAGCCGAA-3' B. 5'-AAGGCCTT-3' C. 5'-AAGCCGTT-3' D. 5'-AAGCGCAA-3' E. 5'-AATTGGCC-3'
B. 5'-AAGGCCTT-3'
If the transcription starts at the arrow, the sequence of the transcribed RNA will be: A. 5'-AGGTC....-3' B. 5'-AGGUC.....-3' C. 5'-TCCAG.....-3' D. 5'-UCCAG.....-3'
B. 5'-AGGUC-3'
A major reason why DNA rather than RNA is used for the storage of genetic information is: A. DNA base pairing is significantly more stable than RNA base pairing B. DNA is more stable then RNA C. only DNA can form anitparallel double strands D. there is no enzyme that can make a complementary copy of RNA
B. DNA is more stable than RNA
Microtubules alternate between growing and shortening states (dynamic instability). The state is controlled by: A. hydrolysis of ATP bound to the tubulin dimer B. hydrolysis of GTP bound to the tubulin dimer
B. hydrolysis of GTP bound to the tubulin dimer
DNA is negatively charged at physiological pH. The tails of histone proteins contain many positively charged lysine amino acids. Enzymes called histone acetyl tranferases (HATs) acetylate these lysine side chains to influence the binding of the histones to their biological ligand. Which of the following statements are true? A. HAT acetylation of the lysines should INCREASE the strength of binding between the histones and DNA B. HAT acetylation of the lysines should DECREASE the strength of binding between the histones and DNA C. HAT acetylation of the lysines should have NO EFFECT because histones do not interact with DNA D. you would predict that there must be histone deacytylases present in cells that can hydrolyze the acetyl group from acetylated lysines E. both A and D are true
B. HAT acetylation of the lysines should DECREASE the strength of binding between the histones and DNA
The most abundant intracellular cation is: A. H+ B. K+ C. Na+ D. Ca++
B. K+
The exposure of a developing embryo to some kinds of peptides can lead to a dramatically new phenotype (for example, a predisposition to certain types of cancer). In most cases, DNA sequencing of the embryo and the mother do not show any changes in genotype. That would be a classic example of: A. Mendelian inheritance of a mutation in a specific gene B. Non-Mendelian inheritance due to an epigenetic change C. Non-Mendelian inheritance of a mutation in a specific gene D. Mendelian inheritance due to an eipgenetic change
B. Non-Mendelian inheritance due to an epigenetic change
When mammalian cells are irradiated with UV light, they stop dividing and arrest at a G1 checkpoint. Place the following events in the order in which they occur. W. production of p21 X. DNA damage signals through ATM Y. inactivation of cyclin-Cdk complex Z. activation of p53 A. W, X, Z, Y B. X, Z, W, Y C. Y, X, W, Z D. Z, W, X, Y
B. X, Z, W, Y
Which of the following statements about enzymes are correct? A. enzymes enable energetically unfavorable reactions (delta G > 0) to occur B. an enzyme preferentially binds to the transition state of the reaction C. an enzyme can typically catalyze many chemically different reactions D. an enzyme can bind to many structurally unrelated substrates E. enzymes are permanently altered after catalyzing a reaction
B. an enzyme preferentially binds to the transition state of the reaction
The dark reactions of photosynthesis are: A. catabolic B. anabolic
B. anabolic
The last common ancestor to plants and animals was a unicellular eukaryote. Thus, it is thought that multicellularity and the attendant demands for cell communication arose independently in these two lineages. This evolutionary viewpoint accounts nicely for the vastly different mechanisms that plants and animals use for cell communication. Fungi use signaling mechanisms and components that are very similar to those used in animals. Which of the phylogenetic trees shown in Figure 41 does this observation support? A. a B. b C. c
B. b
Viagra acts to relax smooth muscle: A. by activating guanylyl cyclase B. by activating NO synthase C. by inhibiting cGMP phosphodiesterase D. by inhibiting a calcium ion channel
B. by activating NO synthase
Ion channels A. allow cells to concentrate ions against a concentration gradient B. can be regulated by a membrane voltage, a specific ligand or mechanical stress C. are nonspecific for Na+, K+, or Ca++ D. are examples of peripheral membrane proteins
B. can be regulated by a membrane voltage, a specific ligand or mechanical stress
The process of breaking down cellular macromolecules is called: A. anabolism B. catabolism
B. catabolism
Microtubules initiate growth at structures called _______ and extend outward toward the periphery of the cell. Hence, the plus end of the microtubules is found at ______. A. peroxisomes/ the cell periphery B. centrosomes/ the cell periphery C. peroxisomes/ the peroxisome D. centrosomes/ the centrosome
B. centrosomes/ the cell periphery
A pseudogene represents a duplication of functional gene that has diverged and is expressed by the cell to preform a new function. A. True B. Flase
B. false
Introns and transposons tend to assist in the evolution of new genes. A. true B. false
B. false
Living cells are always in thermodynamic equilibrium. A. true B. false
B. false
The DNA introns are more highly conserved than the DNA of exons. A. true B. false
B. false
A bacterium is suddenly expelled from a warm human intestine into the cold world outside. Which of the following adjustments might the bacterium make to maintain the same level of membrane fluidity? A. increase the length of the hydrocarbon tails in its membrane phospholipids B. increase the proportion of unsaturated hydrocarbon tails in its membrane phospholipids (more double bonds) C. decrease the proportion of unsaturated hydrocarbon tails in its membrane phospholipids (fewer double bonds) D. decrease the amount of cholesterol in the membrane
B. increase the proportion of unsaturated hydrocarbon tails in its membrane phospholipids (more double bonds)
Which of the following statements regarding lipid membranes is true? A. phospholipids will spontaneously form liposomes in nonpolar solvents B. membrane lipids move laterally within their own layer C. membrane lipids spontaneously flip from one layer of bilayer to the other D. the preferred form of a lipid bilayer in water is a flat sheet with exposed edges
B. membrane lipids move laterally within their own layer
An important function of smooth ER and the sarcoplasmic reticulum of muscle cells is to: A. synthesize proteins destined for secretion from the cell B. modify proteins by the addition of carbohydrate C. degrade ubiquinated proteins D. store or sequester Ca++ that can be used for signaling
B. modify proteins by the addition of carbohydrate
Most genome alterations and mutations have A. positive consequences for organisms B. neutral consequences for organisms C. negative consequences for organisms
B. neutral consequences for organisms
Production of ATP in mitochondria is referred to as: A. substrate-level phosphorylation B. oxidative phosphorylation
B. oxidative phosphorylation
Which of the following statements about chloroplast proteins are true A. all of the chloroplast proteins are synthesized in the chloroplast B. some of the chloroplast proteins are synthesized in the chloroplast, some are imported C. all of the chloroplast proteins are imported
B. some of the chloroplast proteins are synthesized in the chloroplast, some are imported
As DNA polymerase extends a primer, what nucleotide will it incorporate when the template strand contians an A? A. the deoxyribonucleotide U B. the deoxyribonucleotide T C. the ribonucleotide U D. the ribonucleotide T E. both B and D
B. the deoxyribonucleotide T
What is the primary function of mitochondria? A. the generation of oxygen from carbohydrates B. the generation of ATP via oxidative phosphorylation C. the generation of GTP via the reactions of the TCA cycle D. the generation of NAD+ via the fatty acid cycle
B. the generation of ATP via oxidative phosphorylation
DNA can be denatured using heat to cause the two strands to separate. Interestingly, the temperature at which denaturation occurs depends upon the relative proportion of which nucleotides. What is the explanation? A. the greater the % of A in DNA, the higher the temperature needed to denature as A:T base pairs are more stable B. the greater the % of G in the DNA, the higher the temperature needed to denature as G:C base pairs are more stable
B. the greater the % of G in the DNA, the higher the temperature needed to denature as G:C base pairs are more stable
You have identified mutants of an enzyme that catalyzes a commercially useful reaction. Both mutants have the same Vmax as the original or wild type (WT) enzyme. However, one mutant has a lower Km for substrate than the WT, the other has a higher Km for substrate. Which mutant is likely to be a "better" (i.e., faster) enzyme for catalyzing the reaction? A. neither. since they have the same Vmax they will have the same reaction velocities at all substrate concentrations B. the lower the Km enzyme since it will show greater reaction velocities especially at low concentrations of substrate C. the higher Km enzyme since it will show greater reaction velocities especially at higher concentrations of substrate
B. the lower the Km enzyme since it will show greater reaction velocities especially at low concentrations of substrate
The most reliable feature distinguishing a eukaryotic cell from a prokaryotic cell is: A. the absence of a cell wall B. the presence of a nucleus C. the eukaryotic cell's larger size D. the presence of internal membranes E. the presence of more DNA
B. the presence of a nucleus
Why do C4 plants have an elegant shuttle to increase CO2 concentrations near RUBISCO? A. to maximize photorespiration (when plants take up O2 instead of CO2) B. to minimize photorespiration (when plants take up O2 instead of CO2) C. to maximize photophosphorylation (cyclic electron flow used to make ATP) D. to minimize photophosphorylation (cyclic electron flow used to make ATP)
B. to minimize photorespiration (when plants take up O2 instead of CO2)
The distinct characteristics of different cell types in a multicellular organism are produced mainly by the differential regulation in the? A. translation of mRNA B. transcription of genes transcribed by RNA polymerase II C. transcription of housekeeping genes D. inactivation of specific genes E. packing of DNA into nucleosomes in some cells and not others
B. transcription of genes transcribed by RNA polymerase II
A strain of yeast translates mRNA into protein with a high level of inaccuracy. Individual molecules of a particular protein isolated from this yeast have the following variations in the first 11 amino acids compared with the sequence of the same protein isolated from normal yeast cells. What is the most likely cause of this variation in protein sequence? A. a mutation in the spliceosomes that leads to inaccurate RNA splicing B. a mutation in the anticodon of the isoleucine tRNA (tRNAIIe) C. a mutation in the isoleucyl-tRNA synthetase that decreases its ability to distinguish between different amino acids D. a mutation in the isoleucyl-tRNA synthetase theat decreases its ability to distinguish between different tRNA molecules E. a mutation in small subunit of ribosome that allows binding of incorrect tRNA molecules to the A-site
C. A mutation in the isoleucine tRNA synthetase that decreases its ability to distinguish between different amino acids
In order to do the useful work of making new macromolecules cells generate large amounts of _________, used to do chemical work, and _______ which provides high energy electrons used for reduction reactions. A. ADP/NAD+ B. NADPH/ATP C. ATP/NADPH D. AMP/GTP
C. ATP/NADPH
What two mechanisms account for the final accuracy of DNA replication of approximately 1 in 10^9? A. DNA repair and DNA mismatch repair B. DNA repair and proofreading C. DNA mismatch repair and proofreading
C. DNA mismatch repair and proofreading
DNA differs from RNA in: A. the number of different bases used B. the number of phosphates between the sugars in the sugar-phosphate backbone. C. one of the pyrimidines used D. one of the purines used E. the chemical polarity of the polynucleotide chain
C. one of the pyrimidines used
Eukaryotic RNA polymerase II alters its conformation after binding to a promoter as it makes the transition from DNA-binding to the transcription of RNA. RNAP II is modified at its (C or N)- terminal domain by (methylation or phosphorylation). A. C, methylation B. C, phosphorylation C. N, methylation D. N, phosphorylation
C. N, methylation
Four samples of cell have membranes containing a uniform distribution of a fluorescently labeled phospholipid (sample 1) and three fluorescently labeled membrane proteins X, Y, and Z (samples 2-4), respectively. An intense beam of light is shone on each sample. The light beam destroys the fluorescent label in the illuminated area, but the intensity of unbleached molecules diffuse in. The results of this experiment are shown below. Which of the following interpretations is INCONSISTENT with these results? A. A, X is a small freely diffusing protein B. Y is a large freely diffusing protein C. X and Y are part of the same large protein complex D. Z is bound to a component of the cell is bound to a component of the cell cortex or cytoskeleton and is not free to diffuse
C. X and Y are part of the same large protein complex
A large number of different proteins can be expressed from a single eukaryotic gene due to: A. allosteric modifications B. protein degradation C. alternative splicing D. synteny
C. alternative splicing
The local mediator nitric oxide relaxes smooth muscle by stimulating the intracellular enzyme guanylyl cyclase: A. by way of a G-protein-mediated mechanism B. by way of a receptor tyrosine kinase pathway C. by diffusing into cells and stimulating the cyclase directly D. by way of a cell-surface receptor linked to an intracellular signaling pathay E. by activation of the intracellular protein kinases
C. by diffusing into cells and stimulating the cyclase directly
Assembling the individual enzymes required for a multiple step process into a protein machine is likely to increase the efficiency with which the entire process is carried out in all of the following ways EXCEPT: A. by increasing the rate at which the individual enzymes encounter their substrates B. by ordering the reactions sequentially C. by increasing the Vmax of the individual enzymes D. by coordinating the regulation of the individual enzymes E. by coordinating the movement of the enzymes
C. by increasing the Vmax of the individual enzymes
In Figure 17-2 B, there are two important cell/cell junctions. The one connecting the cytoskeletal elements in one cell to its neighbor is a _________. The one near the apical surface that prevents small molecules from passing between the cell is a _________. A. tight junctions/ hemidesmosome B. desmosome/ connexon C. desmosome/ tight junction D. hemidesmosome
C. desmosome/ tight junction
The differences between humans and chimps are largely due to: A. the larger number of genes in the human genome B. unique genes found only in the human genome C. differences in gene regulation D. unique genes found only in the chimp genome
C. differences in gene regulation
Both the small molecule epinephrine and the peptide glucagon bind to G-protein-coupled receptors and activate glycogen breakdown. Therefore, epinephrine and glucagon must: A. bind to different receptors and activate different second messengers B. bind to the same receptors, one intracellular and the other, extracellular C. have very similar structures and bind to the same receptor D. bind to receptors with different ligand-binding sites but similar functions
C. have very similar structures and bind to the same receptor
All of the following are second messengers used inside the cell for signaling except: A. cAMP B. inositol phosphates C. insulin D. Ca++
C. insulin
Fibronectin is a connector molecule that links ______ on the cell surface to ______ in the extracellular matrix. A. integrins/ actin B. actin/ integrins C. intgrins/ collagen D. collagen/ integrins
C. intgrins/ collagen
A poison is added to an in vitro translation mixture containing mRNA molecules with the sequence 5'-AUGAAAAAAAAAAAAUAA-3' has the following effect: the only product made is a Met- Lys- Lys- Lys- Lys peptide that remains attached to the ribosome. What is the most likely way in which the poison acts to inhibit protein synthesis? A. it inhibits binding of the small subunit of the ribosome to mRNA B. it inhibits peptidyl transferase activity C. it inhibits movement of the small subunit relative to the large subunit D. it inhibits release factor E. it mimics release factor
C. it inhibits movement of the small subunit relative to the large subunit
Which of the following statements concerning cell organelles is true? A. mitochondria are the primary site for the synthesis of lipids B. the ER is the center for energy production C. lysosomes are the site for recycling of biological building blocks D. chloroplasts convert sugars into biological energy molecules ATP and NADPH E. the nucleus is the home for all RNA, the ultimate source of all genes
C. lysosomes are the site for recycling of biological building blocks
Which of the following statements is correct? A. ribosomes are large RNA structures composed solely of rRNA B. ribosomes are synthesized entirely in the cytoplasm C. rRNA contains the catalytic activity that joins amino acids together D. a ribosome consists of two equally sized subunits E. a ribosome binds one tRNA at a time
C. rRNA contains the catalytic activity that joins amino acids together
The lipid bilayer is held together mainly by? A. covalent bonding between membrane lipids B. hydrogen bonding between the phospholipid tails C. repulsion between the hydrophobic phospholipid tails and water. D. covalent bonding between the ends of phospholipid tails in opposite layers. E. hydrogen bonding between the head groups of phospholipids
C. repulsion between the hydrophobic phospholipid tails and water
Which of the following represents the high energy bond in a nucleotide like ATP? A. the phosphodiester bond (connecting the 5' hydroxyl to the alpha phosphate) B. the N-glycosidic bond (connecting the base to the sugar) C. the phosphoanhydride bond (connecting two adjacent phosphates) D. none of the above
C. the phosphoanhydride bond (connecting two adjacent phosphates)
Among eukeryotes, plants, animals, and fungi all contain mitochondria, but only animals and fungi use cAMP for cell signaling. These similarities and differences suggest that: A. plants acquired mitochondria after they diverged from animals and fungi B. plants lost the ability to use cAMP as they diverged from animals and fungi C. the precursor to animals and fungi acquired the ability to use cAMP for cell signaling D. animals and fungi separately acquired the ability to use cAMP
C. the precursor to animals and fungi acquired the ability to use cAMP for cell signaling
In DNA mismatch repair how does the protein machinery know which strand of DNA is the "wrong" one that needs to be replaced? A. the repair complex is physically associated only with the new strand B. the repair complex is physically associated only with the old strand C. the repair complex "nicks" on the new strand D. the repair complex "nicks" only the old strand
C. the repair complex "nicks" on the new strand
The function of the light reactions of photosynthesis is to oxidize _________ and reduce ________. A. water, NADPH B. water, NAD+ C. water, NADP+ D. oxygen, NADP+
C. water, NADP+
As a consequence, nucleic acids are synthesized: A. 2' to 5' B. 3' to 5' C. 5' to 2' D. 5' to 3'
D. 5' to 3'
You have an oligonucleotide probe that hybridizes to part of gene A from a eukaryotic cell. Choose whether a cDNA library or a genomic DNA library will be more appropriate to use for the following applications. A) to study the promoter of a gene A. B) to express gene A in bacteria to produce lots of protein A. A. A; cDNA library, B; cDNA library B. A; genomic library, B; genomic library C. A; cDNA library, B; genomic library D. A; genomic library, B; cDNA library
D. A; genomic library, B; cDNA library
The products of the light reactions of photosynthesis include oxygen and: A. glucose B. sucrose C. ATP and NADP+ D. ATP and NADPH
D. ATP and NADPH
The membrane potential of a typical animal cell favors the inward flux of: A. water B. Cl- C. ATP D. Ca2+
D. Ca2+
The most abundant intracellular cation is: A. Na+ B. Ca2+ C. H+ D. K+
D. K+
Which of the following are coenzymes in their reduced form? A. ATP and GTP B. coenzyme A and CoQ C. NAD+ and FAD D. NADH and FADH
D. NADH and FADH
You have identified a protein factor that when added to in vitro protein synthesis reaction increases the incorporation of 35S- methionine from 4pmoles/minute to 8 pmoles/minute. When you centrifuge these reactions and measure polyribosomes and free ribosomes, you observe that more of the ribosomes are present as polyribosomes for the reactions that contain your stimulatory factor. Which explanation is consistent with this result? A. Your factor binds to the small subunit to promote translation initiation B. Your factor binds to the large subunit to promote translation termination C. Your factor binds to the ribosome to decrease the rate of elongation D. Your factor binds to the ribosome to increase the rate of elongation
D. Your factor binds to the ribosome to increase the rate of elongation
Superchick stimulates proliferation of cultured chicken cells. The receptor that binds Superchick is a receptor tyrosine kinase, and many tumor cell lines have mutations in that gene that encodes this receptor. Which of the following types of mutations would be expected to induce uncontrolled cell proliferation? A. a mutation that increases recognition of the receptor by phosphatases B. a mutation that prevents ligand binding C. a mutation that prevents localization of the receptor to the plasma membrane D. a mutation that causes dimerization of the receptor E. a mutation that destroys the kinase activity of the receptor
D. a mutation that causes dimerization of the receptor
Which of the following steps is false? A. all protein molecules function by binding specifically to other molecules (their ligand) B. many proteins can bind to more than one ligand C. binding between protein and ligand generally involves noncovalent bonds D. a protein and ligand interaction of -2kcal/mol would represent a very tight association under normal conditions
D. a protein and ligand interaction of -2kcal/mol would represent a very tight association under normal conditions
Cells can use ATP to: A. drive conformational change, for example, motor proteins B. drive thermodynamically unfavorable reactions C. Phosphorylate proteins to inactivate them D. all of the above
D. all of the above
Reactions that have positive standard free energy changes (delta G0'>0) can be made to occur in cells by: A. coupling them with exergonic reactions via a common intermediate B. manipulating the concentrations of the products and reactants such that delta G<0 C. coupling them to the hydrolysis of ATP D. all of the above
D. all of the above
Reactions with positive standard free energy changes (delta G0>0) can be made to occur in cells by: A. coupling them to the hydrolysis of ATP B. coupling them with exergonic reactions via a common intermediate C. manipulating the concentrations of products and reactants such that delta G<0 D. all of the above
D. all of the above
Recall that G proteins are molecular switches that are turned on by binding of GTP. You have identified a mutation in a G protein that causes the G protein to remain "active" much longer than normal. Which of the following might be the explanation for this: A. the mutant G protein hydrolyzes GTP much more slowly than the normal G protein. B. the mutant G protein can no longer interact with another protein that stimulates the binding of GTP. C. the mutant G protein can no longer interact with another protein that stimulates its hydrolysis of GTP. D. both A and C
D. both A and C
The concentration of a particular protein X in a normal human cell rises gradually from a low point, immediately after cell division, to a high point, just before cell division, and then drops sharply. The level of its mRNA in the cell remains fairly constant throughout this time. Protein X is required for cell growth and survival, but the drop in its level just before cell division is essential for division to proceed. You have isolated a line of human cells that grow in size in culture but cannot divide, and on analyzing these mutants you find that levels of X protein do not decrease. Which of the following mutations could explain these results? A. a mutation that results in the loss of an enzyme that adds a ubiquitin tag to the protein B. a mutation in gene X that results in the loss of polyA addtion to its mRNA C. a mutation in gene X that changes the sequence that encodes sites at which ubiquitin can be attached to the protein D. both A and C
D. both A and C
Which of the following molecular motor proteins is associated with microtubules? A. kinesins B. dyneins C. myosins D. both A and C
D. both A and C
What is a riboswitch? A. a microRNA that inhibits RNAP synthesis B. an RNA that can adopt different conformations upon binding a ligand like a metabolite C. an RNA that can control its own synthesis or translation D. both B and C
D. both B and C
You have isolated a strain of mutant yeast cells that divides normally at 30 degrees Celsius but cannot enter M phase at 37 degrees Celsius. You have isolated its mitotic cyclin and mitotic Cdk and find that both are normal and can form a normal M-Cdk complex at both temperatures. Which of the following temperature-sensitive mutations could be responsible for the behavior of this strain of yeast? A. inactivation of an enzyme that ubiquinates the cyclin B. inactivation of a protein kinase that phosphorylates M-Cdk complex C. inactivation of a protein phosphatase that removes a phosphate from the M-Cdk complex D. both B and C
D. both B and C
A common means of providing energy to an energetically unfavorable reaction in a cell is by: A. generation of a higher temperature by the cell B. transfer of a phosphate group from the substrate ADP C. enzyme catalysis D. coupling of ATP hydrolysis to the reaction E. coupling of the synthesis of ATP to the reaction
D. coupling of ATP hydrolysis to the reaction
Proteins destined to enter the ER: A. cross the membrane in a folded state B. all remain within the ER C. are transported across the membrane after their synthesis is complete D. cross the membrane while being synthesized
D. cross the membrane while being synthesized
Which of the following is NOT true of Nucleosomes? A. they contain histones H2A, H2B, H3, H4 B. the DNA is wrapped in around the histone core almost 2 times C. the histone core contains a total of 8 proteins D. histones are acidic proteins so that they can interact well with DNA E. nucleosomes represent the initial step in the packaging of DNA chromatin
D. histones are acidic proteins so that they can interact well with DNA
The alpha helix and beta sheet are common secondary structures in proteins, both structures are stabilized by: A. hydrogen bonding between the amino acid side chains most commonly found in proteins B. covalent interactions between amino acid side chains and the polypedtide backbone C. ionic interactions between charged amino acid side chains D. hydrogen bonding between atoms of the polypedtide backbone
D. hydrogen bonding between atoms of the polypedtide backbone
All members of the steroid hormone receptor family: A. are cell surface receptors B. do not undergo conformational change upon hormone binding C. are never found in the nucleus D. interact with the signal molecules that diffuse through the plasma membrane E. regulate sexual development
D. interact with the signal molecules that diffuse through the plasma membrane
RNA polymerases I, II, and III respectively transcribe? A. mRNA, tRNA, rRNA B. mRNA, rRNA, tRNA C. rRNA, tRNA, mRNA D. rRNA, mRNA, tRNA
D. rRNA, mRNA, tRNA
When a heterotrimeric G protein is activated by a cell-surface receptor: A. the G-protein undergoes dephosphorylation by a protein phosphatase B. the separate alpha, beta, and gamma subunits assemble into an active complex C. the GTP bound to the alpha, subunit is hydrolyzed to GDP D. the alpha subunit exchanges its bound GDP for GTP and the alpha subunit is dissociated
D. the alpha subunit exchanges its bound GDP for GTP and the alpha subunit is dissociated
Transport in and out of the nucleus occurs: A. large molecules are actively transported out B. small molecules can diffuse in and out C. large molecules are actively transported in D. using all of the above
D. using all of the above
In nerve cell signaling the action potential travels in one direction because: A. the Na+/K+ pump restores the concentrations of Na+ and K+ to their original levels B. the K+ leak channels allow K+ to flow out, restoring the membrane to resting potential C. depolarization of the membrane causes voltage-gated K+ channels to open D. voltage-gated Na+ channels adopt a transitory inactive conformation after being opened E. voltage-gated Na+ channels spend less time in the open conformation when the membrane returns to the resting potential
D. voltage-gated Na+ channels adopt a transitory inactive conformation after being opened
The basic unit of all living things is: A. a gene B. a lipid enclosed compartment C. a lipid enclosed compartment containing DNA D. a virus E. a cell
E. a cell
Homologous DNA recombination can: A. assist in the repair of DNA that has undergone double strand breaks B. swap individual strands of DNA between chromosomes C. introduce or swap double stranded DNA between chromosomes D. increase genetic diversity in a population E. all of the above
E. all of the above
If the coloring of calico cats is due to X chromosome inactivation, which of the following will be true? A. calico cats with identical patterns will be rare B. calico cats will be female C. patches of the same color represent cells that share a chromosome lineage D. genes involved in fur color must reside on the X chromosomes E. all of the above
E. all of the above
In the DNA helix: A. purines pair with pyrimidines B. the strands are antiparallel C. the phosphodiester bonds are 5' and 3' D. thymine is used in place of uracil E. all of the above
E. all of the above
Induced pleuripotent stem cells (iPS) are created directly from adult adult somatic cells. A mouse iPS cell can be implanted in a surrogate female mouse where it grows to become a clone identical to the original donor mouse. This proves that: A. iPS cells can differentiate into different cell types with the appropriate stimulation B. iPS cells are equivalent to embryonic stem cells C. adult somatic stem cells contain all the genes necessary for the regeneration of an individual D. both A and C E. all of the above
E. all of the above
Which of the following steps in protein synthesis require ATP hydrolysis or GTP hydrolysis? A. translocation of the two subunits of the ribosome B. attaching an amino acid to a tRNA C. the release of tRNA from the ribosome D. binding of the small subunit of the ribosome to mRNA E. all of the above
E. all of the above
The expression of the BRF1 gene in mice is normally quite low, but mutations in a gene called BRF2 lead to increased expression of BRF1. You have a hunch that nucleosomes are involved in the regulation of of BRF1 expression and so you investigate the position of nucleosomes over the TATA box of BRF1 in normal mice and in mice that lack either the BRF2 protein (BRF2-) or part of histone H4 (HHF-) (histone H4 is encoded by the HHF gene). In the table below a normal functional gene is indicated by a plus sign (+). Which of the following conclusions CAN be drawn from your data? A. BRF2 is a repressor of BRF1 B. BRF2 and the HHF are required for the specific pattern of nucleosome positions over the BRF1 upstream region C. the specific pattern of nucleosome positioning over the BRF1 upstream region is required for BRF1 repression D. BRF2 protein must interact with histone H4 E. both A and B
E. both A and B
The difference between lipid molecules that form bilayers as opposed to micelles or fat droplets are: A. the molecule must be amphipathetic B. the molecule must have one hydrophobic tail C. the molecule must have two hydrophobic tails D. both A and B E. both A and C
E. both A and C
Which of the following statements about the basic chemistry of cells are true? A. all cells contain the same four types of macromolecules; proteins, polysaccharides, lipids and nucleic acids B. all proteins are constructed from both D and L amino acids C. all genetic instructions in cells are stored in DNA D. all organisms contain the same genes E. both A and C
E. both A and C
The degradation and recycling of the biological macromolecules occurs in the: A. proteasome B. ER C. nucleus D. lysosome E. both A and D
E. both A and D
Which of the following statements are true? A. amino acids are joined together by glycosidic bonds B. the structure of many biological molecules is the result of the hydrophobic effect C. nonpolar amino acids tend to be found in the interior of the proteins D. the amino acid glycine contains the largest amino acid side chain E. both B and C
E. both B and C
You are studying a strain of bacteria that carries a temperature-sensitive mutation in one of the genes required for DNA replication. The bacteria grow normally at the lower temperature but when the temperature is raised they grow extremely slowly. When you test for replication by measuring the incorporation of radioactive deoxynucleotides you observe that new DNA synthesis occurs rapidly at the lower temperature, but not at the higher temperature. Which of the following proteins is most likely to be affected in these bacteria? A. DNA polymerase B. primase C. DNA ligase D. helicase E. loss of function of any of the above could explain your results
E. loss of function of any of the above could explain your results
How do cells change the orientation of phospholipids in the plasma membrane? A. by increasing the fluidity of the lipid bilayer B. by using enzymes which rotate phospholipids through the bilayer (flippases) C. by budding and fusing of membrane vesicles D. by temporary breaks in the bilayer that release the phospholipids from the membrane E. the orientation of the membrane phospholipids cannot be changed
E. the orientation of the membrane phospholipids cannot be changed
Which of the following molecular motors is associated with intermediate filaments? A. kinesins B. dyneins C. myosins D both A and B E. there are no motors associated with intermediate filaments
E. there are no motors associated with intermediate filaments
The Michaelis-Menten (M-M) equation describes the relationship between the initial velocity of an enzyme reaction and the substrate concentration. Complete the M-M equation below: Vo= Vmax
Vo= Vmax ([S]/[S]+Km)
You are studying a particular type of cancer. You observe that the cells are expressing higher then normal levels of the activated version of the G protein Ras (i.e. they contain more Ras-GTP than normal). a. Further study shows that the Ras protein has been mutated, would you classify this as the mutation of a tumor-suppressor gene, or an oncogene? b. Given your knowledge of the regulation of G proteins, suggest an explanation for how this mutant Ras results in more Ras-GTP than normal? c. In a different cancer you also observe an increase in the activated form of Ras, however, in this case, the mutation has occurred in a protein that normally interacts with Ras. The mutation form of the protein no longer interacts with Ras and this leads to inappropriate growth. Since the mutation leads to cancer, would this loss of function be an example of an oncogene or a tumor-suppressor gene? Can you suggest a function of this protein?
a. tumor-suppressor gene b. the mutation would increase Ras kinase activity c. oncogene, the protein could inhibit the GTP receptor.
Codon-Anticodon interactions use classic base-pairing rules for antiparallel stranded nucleic acids. Determine the 5' to 3' sequence of the codon (codons are always written as 5'-3') that would pair with a tRNA containing the anticodon 3'UUC-5'. Refer to the genetic code below to identify which amino acid is attached to the tRNA. The amino acid is ______ 3'-UUC-5' (anticodon) 5'-______-3' (codon)
amino acid- Lys 5'-AAG-3'
Choose from polarizes, depolarizes, Na+, K+, Ca2+, Cl-, activated, inactivated, potential. May use an answer more than once. The channels are named for the ion that they allow through. A stimulus _______ the membrane. The _____ channel (gate) opens, allowing _____ ions into the cell. This channel is quickly _________. Then the _____ channel (gate) opens, allowing ____ ions out of the cell. The resting _____ is reestablished.
depolarizes, activated, K+, inactivated, Na+, potential
For each of the following sentences, fill in the blanks with the best word or phase selected from the list below. Not all words or phrases will be used; each word or phrase should be used only once. Cells can signal to each other in various ways. A signal that must be relayed to the entire body is most efficiently sent by ___________ cells, which produce hormones that are carried throughout the body through the bloodstream. On the other hand, _________ methods of cell signaling do not require the release of a secreted molecule and are used for a very localized signaling events. During __________ signaling, the signal remains in the neighborhood of the secreting cell and thus acts as a local mediator on nearby cells. Finally, __________ signaling involves the conversion of electrical impulses into a chemical signal. Cells receive signals through a _________, which can be an integral membrane protein or can reside inside the cell. Word Bank amplification G-protein phosphorylation contact-dependent K+ channel receptor endocrine neuronal target epithelial paracrine
endocrine, contact-dependent, paracrine, neuronal, receptor
For the three amino acids listed, what is the functional characteristic of its side chain at pH 7? Leucine, R= -CH2CHCH3CH3 Aspartic Acid, R= -CH2COOH Serine, R= -CH2OH Choices: hydrophobic, hydrophilic uncharged, hydrophilic charged
leucine- hydrophobic aspartic acid- hydrophilic charged serine- hydrophilic uncharged
Any substance that will bind to a protein is known as a ______. Enzymes bind to their substrates at the ________. Enzymes catalyze a chemical reaction by stabilizing the formation of the _________. Hexokinase changes conformation when it binds substrates, an example of ____________. Word Bank: transition state, activation energy, high-energy, low-energy, product, substrate, ligand, L-isomer, D-isomer, active site, induced fit.
ligand, active site, transition state, induced fit
In order to transmit a signal from one neuron to another a _____ must be released across the _____. This chemical signal is released when a ______ channel opens triggering the fusion of vesicles with the plasma membrane to release the stored chemical signal. Word Choices: Na+, K+, Ca2+, synapse, dendrite, neurotransmitter, action potential
neurotransmitter, synapse, Ca2+
What are the 4 levels of protein structure and what do they represent?
primary- amino acid chain secondary- alpha helix, beta sheet tertiary- 3D composed of secondary structures quaternary- made up of many subunits
Identify the building blocks and the specific bond that attaches them together for the following macromolecules. Macromolecules Building Block Bond Name Lipid fatty acids ester Proteins Nucleic Acids Carbohydrates
proteins- amino acid, peptide bond nucleic acids- nucleotides, phosphodiester bonds carbohydrates- sugars, glycosidic linkage