CMB Final Exam (Previous Exam Questions)

Kinesin motor proteins use ATP to change their shape and thus can walk along? a) DNA molecules in the nucleus b) the exterior of a cell membrane c) microtubules in cells d) between the inner and outer nuclear membrane e) none of these is correct

(C) microtubules in cells

The genetic information carried by a cell is passed on, generation after generation, with astonishing fidelity. However, genomes are still altered over evolutionary time scales, and even their overall size can change significantly. Which of the following genome-altering events has increased the size of the mammalian genome the most? A) Transposition B) Point mutation C) Chromosomal deletion D) Chromosomal inversion E) Chromosomal translocation

A) Transposition

Which of the following would be most likely to accumulate changes to its sequence? A) a gene that has recently been duplicated in the genome B) a gene that codes for a highly optimized essential protein or RNA molecule C) a gene encoding DNA polymerase D) a regulatory DNA sequence E) a gene that is highly conserved among a wide diversity of organisms

A) a gene that has recently been duplicated in the genome

Which of the following does not occur during M phase in animal cells? A) growth of the cell B) condensation of chromosomes C) breakdown of nuclear envelope D) attachment of chromosomes to microtubules

A) growth of the cell

The telomerase enzyme in human cells A) has an RNA component. B) extends the telomeres by its RNA polymerase activity. C) polymerizes the telomeric DNA sequences without using any template. D) removes telomeric DNA from the ends of the chromosomes. E) creates the "end-replication" problem.

A) has an RNA component.

What part of the DNA replication process would be most directly affected if a strain of bacteria lacking primase were used to make the cell extracts? A) initiation of DNA synthesis B) Okazaki fragment synthesi C) leading-strand elongation D) lagging-strand completion

A) initiation of DNA synthesis

What part of the DNA replication process would be most directly affected if a strain of bacteria lacking primase were used to make the cell extracts? A) initiation of DNA synthesis C) leading-strand elongation D) lagging-strand completion

A) initiation of DNA synthesis

Sodium ions, oxygen (O2), and glucose pass directly through lipid bilayers at dramatically different rates. Which of the following choices presents the correct order, from fastest to slowest? A) oxygen, glucose, sodium ions B) sodium ions, oxygen, glucose C) oxygen, sodium ions, glucose D) glucose, oxygen, sodium ions E) glucose, sodium ions, oxygen

A) oxygen, glucose, sodium ions

The Trp operon in Escherichia coli encodes the components necessary for tryptophan biosynthesis. In the presence of the amino acid in a bacterium A) the tryptophan repressor is bound to the tryptophan operator. B) the tryptophan repressor is bound to bacterial RNA polymerase. C) the expression of the tryptophan repressor is shut off. D) the operon genes are expressed. E) All of the above.

A) the tryptophan repressor is bound to the tryptophan operator.

Which of the following regions of the genome is the least likely to be conserved over evolutionary time? A) the upstream regulatory region of a gene that encodes the region conferring tissue specificity B) the upstream regulatory region of a gene that binds to RNA polymerase C) the portion of the genome that codes for proteins D) the portion of the genome that codes for RNAs that are not translated into protein

A) the upstream regulatory region of a gene that encodes the region conferring tissue specificity

The number of DNA molecules in the prokaryotic bacteria, Escherichia coli, is? a) 1 b) 2 c) 46 d) 1,850 e) about 25.7 million

a) 1

What is the Vmax of the inhibitor-1enzyme reaction? a) 12 mg/min glucose b) 10 mg/min glucose c) 0.6 uM glucose d) 8.0 mg/min glucose e) none of these is a best choice

a) 12 mg/min glucose

Which of the following molecules is(are) made during cyclic photophosphorylation? a) ATP only b) NADPH only c) ATP & NADPH d) FADH2only e) none of these is correct

a) ATP only

An 'evolutionary clock' measures? a) DNA sequence divergence b) the time it takes for one cell's DNA to replicate c) virus replication d) the rate of sedimentation of DNA in a centrifuge e) none of these is a correct choice

a) DNA sequence divergence

The earliest photosynthetic cells probably used which of the following at as a reduction source of hydrogen? a) H2S b) H2O c) CO2 d) C6H12O6 e) NADH

a) H2S

Which of the following is a molecular chaperone? a) HSP-70 b) ubiquitin c) a prion d) proteasomes e) all of these are correct

a) HSP-70

Droplets of hydrophobic molecules surrounded by a skin of water are known as? a) coacervates b) liposomes c) aminoacyl-tRNA synthetases d) viruses e) unknown

a) coacervates

Which of the following early Earth environments should be a best candidate for support chemosynthetic thermophilic bacteria that might have lead to the origins of life. a) deep ocean hydrothermal vents b) asteroids as Bennu and Ryugu c) comets as Rosetta d) Murchison meteorite e) none of these is a likely choice

a) deep ocean hydrothermal vents

The transport of small ligands (molecule of < 5K MW) across outer mitochondrial membranes uses which of these? a) porins b) nuclear localizing proteins c) ATP synthase d) electron transfer chain proteins e) none of these

a) porins

A 3D computer reconstruction of a series of stacked TEM images of cells structures creates an image known as a? a) tomogram b) autoradiograph c) unit membrane d) confocal image e ) none of these

a) tomogram

A major paradigm of cellular biology is that all cells living today can trace their ancestry back to a presumed ancestral cell? a) true b) false

a) true

A most definitive characteristic of living systems is their ability to self-replicate? a) true b) false

a) true

Improvements in the ability of instruments to measure biological parameters of living organism is as important, if not more so, than the hypothesis itself? a) true b) false

a) true

Polycyclic aromatic hydrocarbons have been detected in asteroids? a) true b) false

a) true

Recently 4 synthetically made nucleotide have been incorporated in DNA that has the same physical and chemical properties as DNA containing A,T,G, and C nucleotides and that could also transcribe this 8 based DNA into RNA. a) true b) false

a) true

The linking condensation of Pi to ADP takes place within the beta-polypeptides of the F1 subunits of ATP synthase during oxidative phosphorylation? a) true b) false

a) true

The molecules made abiotically by Stanley Miller were quite similar to the molecules found in meteorites as the Murchison meteorite discovered in Australia? a) true b) false

a) true

The nucleolus has been recently described as a globular structure within the nucleus with a role in ribosome biogenesis. Some have classified it as a protein based liquid globule and thus a membrane-less organelle? a) true b) false

a) true

Staphylococcus aureus has the membrane and wall structure shown in the figure to the right. If we were to stain these cells using the Gram stainprocedure, then the appearance of these bacteria under a light microscope? a) would appear purple-black and be Gram + cells b) would appear pink-ish and be Gram- cells c) would be translucent (clear) and respond to the Gram staining procedure

a) would appear purple-black and be Gram + cells

All biological proteins in living cells are made of? a) α-L amino acids b) α-D amino acids c) β-L amino acids d) δ-amino acids e) none of these

a) α-L amino acids

Each of the following is involved in regulating mitotic Cdk activity except A) cyclin synthesis and degradation. B) Cdk synthesis and degradation. C) Cdk phosphorylation. D) Cdk dephosphorylation. E) All are involved in regulating mitotic Cdk activity.

B) Cdk synthesis and degradation.

Where does most new membrane synthesis take place in a eukaryotic cell? A) in the Golgi apparatus B) in the endoplasmic reticulum C) in the plasma membrane D) on ribosomes

B) in the endoplasmic reticulum

Which of these might be best to use to visualize the surface topography and composition of biological specimens? a) transmission electron microscopy b) scanning electron microscopy c) brightfield microscopy d) fluorescence microscopy the cytoskeleton e) none of these

b) scanning electron microscopy

Viruses exhibit many of the common biochemical processes found in living organisms, but lack the ability? a) to catalyze metabolic reactions b) to reproduce themselves on their own c) to synthesize new molecules d) convert energy to do biological work e) none of these is correct

b) to reproduce themselves on their own

A 3D reconstruction from individual sections of biological specimens, made by computer assisted techniques is made by the process of? a) cryoelectron microscopy b) tomography c) differential interference-contrast microscopy d) darkfield microscopy e) none of these

b) tomography

Which of the following coenzymes is part of the pyruvate dehydrogenase complex (PDH)? a) COA-SH b) NAD+ c) FAD d) lipoate e) choose this answer if all of these are part of PDH

e) choose this answer if all of these are part of PDH

In cell and molecular biology a model organism is one that likely is? a) plentiful b) has a simple genome c) a prolific reproducer d) has unique properties for analysis e) choose this answer if all of these could apply to model organisms

e) choose this answer if all of these could apply to model organisms

Which of the following chemical reactions occurs during the aerobic cell respiration? a) substrate level phosphorylation b) decarboxylation c) reduction d) acylation e) choose this answer if all of these do occur during cell respiration

e) choose this answer if all of these do occur during cell respiration

Which of the following provides support for the hypothesis that all known organism may be derived from a universal common ancestor? a) presence of similar organic molecules in in current living organism b) protein being made of only L-amino acids c) templated polymerization during DNA replication d) a common genetic code e) choose this answer if all of these do support the hypothesis

e) choose this answer if all of these do support the hypothesis

Since cells operate in very narrow temperature ranges and are thus isothermal, free energy changes in chemical reactions in cells are most directly related to? a) the gas constant b) enthalpy c) entropy d) substrate level phosphorylation e) none of these is correct

c) entropy

In the field of proteomics the figure to the right is commonly referred to as a(n)? a) beta sheet b) EF-hand motif c) interactome map d) alpha domain e) none of these is correct

c) interactome map

In the Krebs cycle reaction shown to the right, which of the following types of chemical reactions might be occurring? a) hydrolysis b) condensation c) oxidation-reduction d) phosphorylation e) choose this answer if none of the above is occurring

c) oxidation-reduction

The phrase "Knowing the parts may explain the function of the whole" is descriptive of which of the following procedural experimental techniques of cell and molecular biology? a) staining of cells b) growing cells in culture c) reductionism (grind & find) d) mitosis e) none of these is a correct choice

c) reductionism (grind & find)

Which of the following organelle components is responsible for phosopholipid synthesis and detoxification of some chemicals? a) rough endoplasmic reticulum b) lysosomes c) smooth endoplasmic reticulum d) Golgi complex e) none of these is correct

c) smooth endoplasmic reticulum

During the Krebs cycle GTP is formed by? a) oxidative phosphorylation b) cyclic phosphorylation c) substrate level phosphorylation d) acylation e) GTP is not formed during the Krebs cycle

c) substrate level phosphorylation

Which of the following would favor an "RNA world" hypothesis? a) the fact that DNA can encode genetic information b) the fact that proteinaceous enzymes can catalyze biological reactions c) the discovery of new life forms that encode their genetic info in RNA and not DNA d) the discovery that some RNA molecules have catalytic activity e) choose this answer if none of these is correct

c) the discovery of new life forms that encode their genetic info in RNA and not DNA

The native conformation of all proteins is? a) helical b) due solely to disulfide bonds c) the most thermodynamically stable 3D orientation d) found only in multimeric proteins e) none of these is correct

c) the most thermodynamically stable 3D orientation

Proteolytic enzymes including trypsin, elastase, and chymotrypsin, which are found in both prokaryotes and eukaryotes, all having the same 3 amino acids (HIS, ASP, & SER) at the active sites are? a) the globulin proteins b) all peroxidases c) the serine proteases d) found only in the nucleus e) unknown in nature

c) the serine proteases

Which of the following model organisms has served as a system to analyze the development of vertebrate body tissue? a) viruses b) roundworm (C. elegans) c) zebra fish d) yeast cells e) none of these is a best choice

c) zebra fish

Messenger RNAs of cells can be silenced (degraded rapidly or sequestered) by? a) tRNA b)DNA c)miRNA d) bacteriorhodopsin e) none of these is correct

c)miRNA

A polymorphic protein is described as one that? a) has a signal sequence b) always contains SER at the active site c) has a non-varying amino acid sequence compared to other proteins with different properties d) varies in amino acid sequence but has same catalytic activity as other proteins e) none of these is correct

d) varies in amino acid sequence but has same catalytic activity as other proteins

The molecule occurring in the greatest amount in cells is? a) DNA b) protein c) glucose d) water e) none of these is correct

d) water

A researcher would like to film the movement of chromosomes during cell division. The best choice of the type of microscope to use would be? a) a light microscope because of its very high resolving power b) a transmission electron microscope because of it magnifying power c) a scanning electron microscope because the specimen is shadow cast d) a transmission electron microscope because of its great resolving power e) a light microscope because the specimen is alive

e) a light microscope because the specimen is alive

Prokaryotic geometric organelles? a) are microcompartment in many bacteria phyla b) are of made hexagonal tiles forming 12 -sided faces c) resemble 12-sided dice d) include the carboxysome of cyanobacteria containing the enzyme Rubisco e) all of the above are correct

e) all of the above are correct

An advantage of hydrophobic molecules, as phospholipids, in living cells is? a) spontaneous self-assembly b) repulsion of large hydrophilic molecules c) formation of bilayers d) reassembly of a torn bilayer e) all of these are advantages of these hydrophobics

e) all of these are advantages of these hydrophobics

In searching for extraterrestrial life the key chemical fingerprints of life one might best look for should include? a) water vapor b) methane c) carbon dioxide d) oxygen e) all of these would be key molecules to search for

e) all of these would be key molecules to search for

Which of the following is mismatched? a) Photosystem I - uses the P700 molecule in its photo-reaction-center b) PGA (phosphoglyceric acid) - is a 3-carbon compound c) an antenna complex - contains hundreds of pigment molecules d) C4 plants - reduce CO2 in bundle sheath cells to reduce photorespiration e) choose this answer if all of the above are correctly matched

e) choose this answer if all of the above are correctly matched

Approximately what percent of the human genome codes for proteins? A) 1.5% B) 10% C) 25% D) 50%

A) 1.5%

Consider the apical location of a particular protein expressed in epithelial cells, illustrated in part A of the figure. When a molecule that chelates calcium is added to the cell culture medium, you observe a redistribution of that protein around the entire cell, shown in part B of the figure. Which is most likely to be true about the role of calcium in maintaining an apical distribution of protein A? A) Calcium is required to maintain the structural integrity of the junctional complex. B) Calcium is required for the binding of the junctional proteins to the cell cortex. C) Calcium is a structural component of protein A. D) Calcium inhibits the intracellular transport of protein A.

A) Calcium is required to maintain the structural integrity of the junctional complex.

Many antibiotics work by inhibiting bacterial protein synthesis. Investigators have isolated a promising new compound and wish to determine its mechanism of action. Using a cell-free translation system similar to the ones originally used to deduce the genetic code, the researchers incubate their drug with the synthetic polynucleotide 5'-AUGUUUUUUUUU. In the absence of the drug, this polynucleotide directs the synthesis of the peptide Met-Phe-Phe-Phe. When the drug is added, only the peptide Met-Phe is produced. Based on this observation, which is most likely the mechanism of action of this potential new antibiotic? A) It blocks translocation of the large ribosomal subunit, preventing the movement of peptidyl-tRNA from the A site to the P site of the ribosome. B) It inhibits the peptidyl transferase activity of the large ribosomal subunit. C) It blocks binding of aminoacyl-tRNA to the A site of the ribosome. D) It inhibits peptide bond formation.

A) It blocks translocation of the large ribosomal subunit, preventing the movement of peptidyl-tRNA from the A site to the P site of the ribosome.

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

A) It is bound by cytoplasmic proteins that direct the nuclear protein to the nuclear pore.

A subset of breast cancers overexpress the receptor tyrosine kinase (RTK), known as human epidermal growth factor receptor 2 (HER2). Patients with HER2-positive breast cancers often benefit from treatment with a HER2-binding antibody known as Pertuzumab. Given that antibodies are large proteins that cannot cross the cell membrane, what might be directly impacted by Pertuzumab to limit cell proliferation? A) Pertuzumab prevents receptor dimerization. B) Pertuzumab prevents changes in gene expression by preventing transcription factor phosphorylation. C) Pertuzumab prevents adaptor protein binding to activated receptors. D) Pertuzumab prevents receptor coupling to G proteins.

A) Pertuzumab prevents receptor dimerization.

Mitogens are A) extracellular signals that stimulate cell division. B) transcription factors important for cyclin production. C) kinases that cause cells to grow in size. D) produced by mitotic cells to keep nearby neighboring cells from dividing.

A) extracellular signals that stimulate cell division.

An elongating ribosome is bound to appropriate tRNAs in both the A and the P sites and is ready for peptidyl transfer. What happens next? A) The carboxyl end of the polypeptide chain is released from the P-site tRNA and joined to the free amino group of the amino acid linked to the A-site tRNA. B) The amino end of the polypeptide chain is released from the P-site tRNA and joined to the free carboxyl group of the amino acid linked to the A-site tRNA. C) The carboxyl end of the amino acid is released from the A-site tRNA and joined to the free amino group of the polypeptide chain linked to the P-site tRNA. D) The amino end of the amino acid is released from the A-site tRNA and joined to the free carboxyl group of the polypeptide chain linked to the P-site tRNA.

A) The carboxyl end of the polypeptide chain is released from the P-site tRNA and joined to the free amino group of the amino acid linked to the A-site tRNA.

Which of the following statements about secretion is TRUE? A) The membrane of a secretory vesicle will fuse with the plasma membrane when it discharges its contents to the cell's exterior. B) Vesicles for regulated exocytosis will not bud off the trans Golgi network until the appropriate signal has been received by the cell. C) The signal sequences of proteins destined for constitutive exocytosis ensure their packaging into the correct vesicles. D) Proteins destined for constitutive exocytosis aggregate as a result of the acidic pH of the trans Golgi network.

A) The membrane of a secretory vesicle will fuse with the plasma membrane when it discharges its contents to the cell's exterior.

Ricin is one of the most powerful toxins known. The protein consists of two subunits: the A chain is an enzyme that inhibits translation and the B chain is a lectin that binds to carbohydrates on the cell surface. What is the most likely mechanism by which ricin enters the cell? A) The protein is internalized by endocytosis. B) The A chain binds to clathrin. C) The protein enters through pore complexes in the plasma membrane. D) The B chain interacts with SNAREs. E) The A chain stimulates autophagy.

A) The protein is internalized by endocytosis.

In bacteria, the transport of many nutrients, including sugars and amino acids, is driven by the electrochemical H+ gradient across the plasma membrane. In E. coli, for example, an H+-lactose symporter mediates the active transport of the sugar lactose into the cell. Given what you know about coupled transport, which is likely true of the H+-lactose symporter? A) The transporter oscillates randomly between states in which it is open to either the extracellular space or the cytosol. B) Lactose and H+ ions bind to two different conformations of the transporter. C) The transporter goes through an intermediate state in which the lactose-binding site is open to both sides of the membrane. D) If the H+ gradient were reversed, the transporter could serve as an H+-lactose antiport. E) To undergo the conformational change that releases lactose into the cell, the transporter hydrolyzes ATP.

A) The transporter oscillates randomly between states in which it is open to either the extracellular space or the cytosol.

Porin proteins form large, barrel-like channels in the membrane. Which of the following statements about these channels is FALSE? A) They are made primarily of α helices. B) They are made primarily of β sheets. C) They cannot form narrow channels. D) They have alternating hydrophobic and hydrophilic amino acids.

A) They are made primarily of α helices.

Which of the following best describes the mechanism by which chromatin-remodeling complexes "loosen" the DNA wrapped around the core histones? A) They use energy derived from ATP hydrolysis to change the relative position of the DNA and the core histone octamer. B) They chemically modify the DNA, changing the affinity between the histone octamer and the DNA. C) They remove histone H1 from the linker DNA adjacent to the core histone octamer. D) They chemically modify core histones to alter the affinity between the histone octamer and the DNA.

A) They use energy derived from ATP hydrolysis to change the relative position of the DNA and the core histone octamer.

Which membrane would show a more rapid recovery of fluorescence in a FRAP study? A) a membrane containing a larger proportion of unsaturated fatty acids B) a membrane containing equal amounts of saturated and unsaturated fatty acids C) a membrane containing a larger proportion of saturated fatty acids D) The saturation of fatty acids in a cell membrane does not affect the speed of fluorescence recovery in a FRAP study. E) a membrane containing a large amount of cholesterol

A) a membrane containing a larger proportion of unsaturated fatty acids

Proteins that are fully translated in the cytosol and lack a sorting signal will end up in the A) cytosol. B) mitochondria. C) interior of the nucleus. D) nuclear membrane.

A) cytosol.

Researchers assayed the activity of enzyme F in three different types of tissue from the same mouse by determining the amount of enzyme product produced per milligram of tissue per unit time. As shown in the graph below, results indicate more product generation in the liver compared to the kidney and muscle samples. Which of the following factors would not explain the different results among the three tissues? A) differences in the DNA content among the tissue types B) differences in the transcription of the gene encoding the enzyme among the tissue types C) differences in the post-translational modifications of the enzyme among the tissue types D) differences in the translation of the mRNA encoding the protein among the tissue types

A) differences in the DNA content among the tissue types

On the ribosome, the mRNA is read from ..., and the polypeptide chain is synthesized from A) 5' to 3'; C- to N-terminus. B) 5' to 3'; N- to C-terminus. C) 3' to 5'; C- to N-terminus. D) 3' to 5'; N- to C-terminus.

B) 5' to 3'; N- to C-terminus.

The sequence of the coding strand of a DNA molecule (that is, the DNA strand that contains the codons specifying the protein sequence) is 5'-CGGATGCTTA-3'. What is the sequence of the RNA made from this DNA? A) 5'-UAAGCAUCCG-3' B) 5'-CGGAUGCUUA-3' C) 5'-AUUCGUAGGC-3' D) 5'-TAAGCATCCG-3' E) 5'-GCCUACGAAU-3'

B) 5'-CGGAUGCUUA-3'

Which of the following describes the Lac operon in E. coli when lactose, but not glucose, is present in the culture medium? A) Neither CAP nor the Lac repressor is bound to the Lac operon's regulatory DNA, and the Lac operon is not expressed. B) CAP, but not the Lac repressor, is bound to the Lac operon's regulatory DNA, and the Lac operon is expressed. C) The Lac repressor, but not CAP, is bound to the Lac operon's regulatory DNA, and the Lac operon is not expressed. D) Neither CAP nor the Lac repressor is bound to the Lac operon's regulatory DNA, and the Lac operon is expressed. E) CAP and the Lac repressor are both bound to the Lac operon's regulatory DNA, and the Lac operon is not expressed.

B) CAP, but not the Lac repressor, is bound to the Lac operon's regulatory DNA, and the Lac operon is expressed.

You are working in a biotech company that has discovered a small-molecule drug called H5434. H5434 binds to LDL receptors when they are bound to cholesterol. H5434 binding does not alter the conformation of the LDL receptor's intracellular domain. Interestingly, in vitro experiments demonstrate that addition of H5434 increases the affinity of LDL for cholesterol and prevents cholesterol from dissociating from the LDL receptor even in acidic conditions. Which of the following is a reasonable prediction of what may happen when you add H5434 to cells? A) Cytosolic cholesterol levels will remain unchanged relative to normal cells. B) Cytosolic cholesterol levels will decrease relative to normal cells. C) The LDL receptor will remain on the plasma membrane. D) The uncoating of vesicles will not occur.

B) Cytosolic cholesterol levels will decrease relative to normal cells.

Under which of the following conditions is the Lac operon in Escherichia coli fully turned on? A) Low glucose and lactose levels B) Low glucose but high lactose levels C) High glucose but low lactose levels D) High glucose and lactose levels E) Low cAMP and high glucose levels

B) Low glucose but high lactose levels

Which of the following would most reliably suggest that a genomic sequence is functionally important? A) The presence of a long open reading frame in the sequence B) Multispecies conservation of the sequence C) Low copy number variation of the sequence D) The presence of active chromatin marks over the sequence

B) Multispecies conservation of the sequence

Which of the following is correct regarding the mutation rate of genomic DNA in different organisms? A) Human cells have a much higher mutation rate compared to bacteria when the rate is normalized to a single round of replication over the same length of DNA. B) Mutation rates limit the number of essential genes in an organism's genome. C) Mutations in the somatic cells cannot be lethal. D) Even if the mutation rate was 10 times higher than its current value, germ-cell stability in humans would not have been affected. E) All of the above.

B) Mutation rates limit the number of essential genes in an organism's genome.

Which of the following statements about the endoplasmic reticulum (ER) is FALSE? A) The ER is the major site for new membrane synthesis in the cell. B) Proteins to be delivered to the ER lumen are synthesized on the smooth ER. C) Steroid hormones are synthesized on the smooth ER. D) The ER membrane is contiguous with the outer nuclear membrane.

B) Proteins to be delivered to the ER lumen are synthesized on the smooth ER.

Investigators are studying a signaling pathway in which an RTK activates the monomeric GTPase Ras. They discover that two new proteins, A and B, have a role in this signaling pathway: cells in which either of these proteins is disabled by mutation no longer show a response to the signal molecule that binds to the RTK. To determine the order in which these proteins act, investigators introduce a continuously active form of Ras into each mutant cell line and record whether this treatment restores signaling. Based on the results shown above, which of the following best represents the signaling pathway under investigation? A) RTK → Protein A → Ras → Protein B → → cell response B) RTK → Protein B → Ras → Protein A → → cell response C) RTK → Protein A → Protein B → Ras → → cell response D) RTK → Ras → Protein A → Protein B → → cell response E) The results are insufficient to make any prediction about the order in which the proteins act in the signaling pathway.

B) RTK → Protein B → Ras → Protein A → → cell response

The figure shows the organization of a protein that normally resides in the plasma membrane. The boxes labeled 1 and 2 represent membrane-spanning sequences and the arrow represents a site of action of signal peptidase. Given this diagram, which of the following statements must be TRUE? A) The N-terminus of this protein is cytoplasmic. B) The C-terminus of this protein is cytoplasmic. C) The mature version of this protein will span the membrane twice, with both the N- and C-terminus in the cytoplasm. D) none of these answers are correct.

B) The C-terminus of this protein is cytoplasmic.

To crack the genetic code, researchers introduced synthetic messenger RNAs into in vitro translation systems and determined which proteins were produced from these synthetic mRNAs. mRNAs consisting of poly-UUC led to production of three different proteins: poly-Phe, poly-Ser, and poly-Leu. What best explains this result? A) Each amino acid is specified by several codons. B) Transcription started at three different places. C) The synthetic mRNA was read in all three reading frames. D) Each codon codes for several different amino acids.

B) Transcription started at three different places.

Studying the expression of a transcription regulatory protein in two cell types, you have performed experiments showing that the mRNA encoding the protein is present at comparable levels in the cytosol of both cell types. However, based on the expression of its target genes, you suspect that the protein activity might be significantly different in the two cell types. Which of the following steps in expression of the gene encoding this protein is more likely to be differentially controlled in these cell types? A) Transcription B) Translation C) mRNA transport D) mRNA degradation

B) Translation

IP3 signaling helps regulate sweating, which is important for regulating body temperature. Anhidrosis, the inability to sweat normally, can be caused by genetic and environmental factors. A rare mutation has been identified in a family with several children suffering from anhidrosis. The mutation inactivates the protein that IP3 binds on the ER membrane. Suppose cells were isolated from affected family members and exposed to different treatments. Which of the following treatments would be able to repair the signaling defect in cells isolated from these patients? A) addition of high amounts of IP3 in the cell B) addition of high amounts of Ca2+ in the cytosol C) activation of phospholipase Cβ in the cell D) addition of PKC to the cell

B) addition of high amounts of Ca2+ in the cytosol

Protein subunits that interact specifically with DNA sequences A) typically recognize sequences of two to three nucleotide pairs in length. B) do so via hydrogen bonds, ionic bonds, and hydrophobic interactions. C) typically form about five weak interactions at the protein-DNA interface. D) often bind loosely to DNA. E) All of the above.

B) do so via hydrogen bonds, ionic bonds, and hydrophobic interactions.

Which of the following occur WITHOUT coupling transport of the solute to the movement of a second solute? A) import of glucose into gut epithelial cells B) export of Ca2+ from the cytosol C) export of H+ from animal cells for pH regulation D) the export of Na+ from cells to maintain resting membrane potential

B) export of Ca2+ from the cytosol

A mutant yeast strain stops proliferating when shifted from 25°C to 37°C. When these cells are analyzed at the two different temperatures, using a machine that sorts cells according to the amount of DNA they contain, the graphs in the figure are obtained. Which of the following would NOT explain the results with the mutant? A) inability to initiate DNA replication B) inability to begin M phase C) inability to activate proteins needed to enter S phase D) inappropriate production of a signal that causes the cells to remain in G1

B) inability to begin M phase

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

B) inactivation of an enzyme that ubiquitylates M cyclin

It has been shown that inhibition of a key chromatin remodeling complex known as NuRD, by deleting one of its subunits, can result in a significant increase in the efficiency of reprogramming of somatic cells into pluripotent stem cells. The reprogramming is normally done by the induced expression of a battery of transcription factors in the somatic cells, but is typically not very efficient. Such an observation suggests that the NuRD complex is normally involved in A) erasing the epigenetic memory in somatic cells. B) maintaining the epigenetic memory in somatic cells. C) preventing DNA replication. D) formation of extended loops from chromosome territories.

B) maintaining the epigenetic memory in somatic cells.

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

B) the binding of a cyclin to Cdk is required for Cdk enzymatic activity.

You have engineered the X chromosomes in female mice such that one X chromosome expresses green fluorescent protein when active, while the other expresses red fluorescent protein. You have used these mice to study cancer in females. You know that each tumor is a clonal cellular proliferation, meaning all of its proliferating cells are descendants of a single original cancer-causing cell. It follows that, unless X-chromosome inactivation is perturbed in tumors A) all tumor cells in one mouse should express the same fluorescent protein (either red or green), but tumor cells from different mice can show either red or green fluorescence. B) the cells in any tumor should all express the same fluorescent protein (either red or green), but independently derived tumors in the same mouse can show either green or red fluorescence. C) different cells within each tumor can express different fluorescent proteins, and the tumors would therefore show yellow fluorescence, but each cell shows either red or green fluorescence. D) each cell can express both fluorescent proteins and would therefore emit yellow fluorescence, and the tumors would glow in yellow as well. E) different tumors would show red, yellow, or green fluorescence.

B) the cells in any tumor should all express the same fluorescent protein (either red or green), but independently derived tumors in the same mouse can show either green or red fluorescence.

3. The position effect variegation (PEV) phenotype described in this chapter can be used to identify new genes that regulate heterochromatin formation. For instance, strains of Drosophila melanogaster with the White variegation phenotype have been subjected to mutagenesis to screen for dominant mutations (in other genes) that either enhance or suppress PEV, meaning the mutations result in either lower or higher red pigment production, respectively. Which of the following mutations is expected to be an enhancer of variegation? A) A mutation that results in the loss of function of the fly's HP1 (heterochromatin protein 1) gene. B) A loss-of-function mutation in a gene encoding a histone deacetylase that deacetylates lysine 9 on histone H3. C) A gain-of-function mutation in a gene encoding a histone methyl transferase that trimethylates lysine 9 on histone H3, resulting in a hyperactive form of the enzyme. D) A gain-of-function mutation in a gene encoding a histone acetyl transferase that normally acetylates lysine 9 on histone H3, resulting in higher expression of the protein.

C) A gain-of-function mutation in a gene encoding a histone methyl transferase that trimethylates lysine 9 on histone H3, resulting in a hyperactive form of the enzyme.

What is the main source of the free energy for the mechanical work performed by DNA helicases during DNA replication in our cells? A) The hydrogen-bonding energy in the DNA double helix B) Thermal energy in the nucleus C) ATP hydrolysis by the helicase D) The energy of SSB binding to single-stranded DNA E) ATP hydrolysis by DNA topoisomerases

C) ATP hydrolysis by the helicase

Which of the following features is common between the replication origins in Escherichia coli and Saccharomyces cerevisiae? A) They both normally exist in one copy per genome. B) Both are specified by DNA sequences of tens of thousands of nucleotide pairs. C) Both contain sequences that attract initiator proteins, as well as stretches of DNA rich in A-T base pairs. D) Both contain GATC repeats that are methylated to prevent the inappropriate "firing" of the origin. E) All of the above.

C) Both contain sequences that attract initiator proteins, as well as stretches of DNA rich in A-T base pairs.

The figure shows that intracellular signaling pathways can be highly interconnected. From the information in the figure which of the following statements is FALSE? A) The GPCR and the RTK both activate phospholipase C. B) Activation of either the GPCR or the RTK will lead to activation of transcriptional regulators. C) CaM-kinase is only activated when the GPCR is active and not when the RTK is active. D) Ras is activated only when the RTK is active and not when the GPCR is active.

C) CaM-kinase is only activated when the GPCR is active and not when the RTK is active.

Cells have oligosaccharides displayed on their cell surface that are important for cell-cell recognition. Your friend discovered a transmembrane glycoprotein, GP1, on a pathogenic yeast cell that is recognized by human immune cells. He decides to purify large amounts of GP1 by expressing it in bacteria. To his purified protein he then adds a branched 14-sugar oligosaccharide to the asparagine of the only Asn-X-Ser sequence found on GP1. Unfortunately, immune cells do not seem to recognize this synthesized glycoprotein. Which of the following statements is a likely explanation for this problem? A) The oligosaccharide should have been added to the serine instead of the asparagine. B) The oligosaccharide should have been added one sugar at a time. C) The oligosaccharide needs to be further modified before it is mature. D) The oligosaccharide needs a disulfide bond.

C) The oligosaccharide needs to be further modified before it is mature.

Since cancer is caused by mutations in genes, most mutagens are considered carcinogenic compounds. Thus, a simple test to see whether or not a compound is mutagenic is highly useful. A variation on the mutation rate assay shown below provides a simple assessment of the mutagenic ability of agents. In this variation, two histidine-requiring E. coli cultures are grown in parallel. Both are inoculated into histidine-containing medium. Culture B medium also contains a potential mutagenic agent, while culture A does not. Later, each culture is spread on its own plate on a medium lacking histidine, and cells that can produce their own histidine grow into visible colonies. If culture B is exposed to a mutagen, what is the expected result? A) Culture B will have fewer colonies on the histidine-minus plate than culture A. B) Culture B will not have any colonies at all due to the detrimental nature of mutagens. C) Culture B will have more colonies on the histidine-minus plate than culture A. D) Culture B will have the same number of colonies as culture A.

C) Culture B will have more colonies on the histidine-minus plate than culture A.

How does a eukaryotic cell deal with the superhelical tension in its genomic DNA resulting from the activity of RNA polymerases? A) DNA gyrase introduces negative supercoils, keeping the DNA under constant tension. B) The RNA polymerases are allowed to rotate freely around their templates during transcription, leading to the relaxation of the tension. C) DNA topoisomerases rapidly remove the superhelical tension caused by transcription. D) The nucleosomes adjust the tension by binding to positively supercoiled regions behind a moving RNA polymerase. E) All of the above.

C) DNA topoisomerases rapidly remove the superhelical tension caused by transcription.

How does S-Cdk help guarantee that replication occurs only once during each cell cycle? A) It blocks the rise of Cdc6 concentrations early in G1. B) It phosphorylates and inactivates DNA helicase. C) It phosphorylates and inactivates Cdc6. D) It promotes the assembly of a prereplicative complex.

C) It phosphorylates and inactivates Cdc6.

Which of the following statements is TRUE? A) Phospholipids will spontaneously form liposomes in nonpolar solvents. B) In eukaryotes, all membrane-enclosed organelles are surrounded by one lipid bilayer. C) Membrane lipids diffuse within the plane of the membrane. D) Membrane lipids frequently flip-flop between one monolayer and the other.

C) Membrane lipids diffuse within the plane of the membrane.

Your friend works in a biotechnology company and has discovered a drug that blocks the ability of Ran to exchange GDP for GTP. What is the most likely effect of this drug on nuclear transport? A) Nuclear transport receptors would be unable to bind cargo. B) Nuclear transport receptors would be unable to enter the nucleus. C) Nuclear transport receptors would be unable to release their cargo in the nucleus. D) Nuclear transport receptors would interact irreversibly with the nuclear pore fibrils.

C) Nuclear transport receptors would be unable to release their cargo in the nucleus.

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

C) QGF activates different intracellular signaling pathways in heart muscle cells, fibroblasts, and nerve cells to produce the different responses observed.

Imagine a chromosome translocation event that brings a gene encoding a histone acetyl transferase enzyme from its original chromosomal location to a new one near heterochromatin. Which of the following scenarios is definitely NOT going to happen? A) The gene gets silenced due to heterochromatin expansion, leading to the misregulation of gene expression for a number of critical genes. B) The translocation event also brings along a chromatin barrier that can prevent heterochromatin expansion into the gene, and there is no phenotypic anomaly. C) Since the gene encodes a histone acetyl transferase, it resists heterochromatin expansion by acetylating its own histones. D) The level of the gene product decreases due to a position effect, leading to an imbalance in the chromatin state of the cell that results in the activation of programmed cell death.

C) Since the gene encodes a histone acetyl transferase, it resists heterochromatin expansion by acetylating its own histones.

Sometimes, chemical damage to DNA can occur just before DNA replication begins, not giving the repair system enough time to correct the error before the DNA is duplicated. This gives rise to mutation. If the adenosine in the sequence TCAT is depurinated and not repaired, which of the following is the point mutation you would observe after this segment has undergone two rounds of DNA replication? A) TCGT B) TAT C) TCT D) TGTT

C) TCT

Which of the following statements about the carbohydrate coating of the cell surface is FALSE? A) It is not usually found on the cytosolic side of the membrane. B) It can play a role in cell-cell adhesion. C) The arrangement of the oligosaccharide side chains is highly ordered, much like the peptide bonds of a polypeptide chain. D) Specific oligosaccharides can be involved in cell-cell recognition.

C) The arrangement of the oligosaccharide side chains is highly ordered, much like the peptide bonds of a polypeptide chain.

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

C) The cell would enter M phase under conditions when normal cells would not.

The signaling pathways shown integrate information provided by signal 1 and signal 2 to activate the transcription of a target gene and trigger a cell response. The intracellular signaling molecules in the pathway are onlyactive when they receive an activating signal (→) from an upstreamsignaling molecule and are not being inhibited (—I) by any upstream signaling molecule. Given this information, under what conditions will the target gene for this signaling network be expressed? A) The target gene will be expressed only when both signals are present. B) The target gene will be expressed only when signal 1 is present. C) The target gene will be expressed when either signal is present on its own. D) The target gene will be expressed only when both signals are absent. E) The target gene will be expressed only when signal 2 is present.

C) The target gene will be expressed when either signal is present on its own.

Which one of the following is the main reason that a typical eukaryotic gene is able to respond to a far greater variety of regulatory signals than a typical prokaryotic gene or operon? A) Eukaryotes have three types of RNA polymerase. B) Eukaryotic RNA polymerases require general transcription factors. C) The transcription of a eukaryotic gene can be influenced by proteins that bind far from the promoter. D) Prokaryotic genes are packaged into nucleosomes.

C) The transcription of a eukaryotic gene can be influenced by proteins that bind far from the promoter.

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

C) The α subunit exchanges its bound GDP for GTP.

What is the most likely explanation of why the overall mutation rates in bacteria and in humans are roughly similar? A) Cell division needs to be fast. B) Most mutations are silent. C) There is a narrow range of mutation rates that offers an optimal balance between keeping the genome stable and generating sufficient diversity in a population. D) It benefits a multicellular organism to have some variability among its cells.

C) There is a narrow range of mutation rates that offers an optimal balance between keeping the genome stable and generating sufficient diversity in a population.

Which of the following statements is not true about the differences between liver cells and kidney cells in the same organism? A) They express different genes. B) They contain the entire set of instructions needed to form the whole organism. C) They contain different genes. D) They contain different proteins.

C) They contain different genes.

Three phospholipids, X, Y, and Z, are distributed in the plasma membrane as indicated in the figure. For which of these phospholipids does a flippase probably exist? A) X only B) Z only C) X and Y D) Y and Z

C) X and Y

You are interested in how cyclic-AMP-dependent protein kinase A (PKA) functions to affect learning and memory, and you decide to study its function in the brain. It is known that, in the cells you are studying, PKA works via a signal transduction pathway like the one depicted in the figure. Furthermore, it is also known that activated PKA phosphorylates the transcriptional regulator called Nerd that then activates transcription of the gene Brainy. Which situation described below will lead to an increase in Brainy transcription? A) a mutation in the Nerd gene that produces a protein that cannot be phosphorylated by PKA B) a mutation in the nuclear import sequence of PKA from PPKKKRKV to PPAAAAAV C) a mutation in the gene that encodes cAMP phosphodiesterase that makes the enzyme inactive D) a mutation in the gene that encodes adenylyl cyclase that renders the enzymeunable to interact with the α subunit of the G protein

C) a mutation in the gene that encodes cAMP phosphodiesterase that makes the enzyme inactive

Which of the following changes is least likely to arise from a point mutation in a regulatory region of a gene? A) a mutation that changes the time in an organism's life during which a protein is expressed B) a mutation that eliminates the production of a protein in a specific cell type C) a mutation that changes the subcellular localization of a protein D) a mutation that increases the level of protein production in a cell

C) a mutation that changes the subcellular localization of a protein

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

C) a mutation that inactivates the protein tyrosine phosphatase that normally removes the phosphates from tyrosines on the activated receptor

In skeletal muscle cells, epinephrine (adrenaline) stimulates the breakdown of glycogen by activating a GPCR. In the signaling pathway here, which step does not amplify the original signal?activation of phosphorylase kinase by activated PKA A) activation of a G protein by an activated GPCR B) production of cyclic AMP by activated adenylyl cyclase C) activation of adenylyl cyclase by an activated G protein D) activation of glycogen phosphorylase by activated phosphorylase

C) activation of adenylyl cyclase by an activated G protein

Most proteins destined to enter the endoplasmic reticulum A) are transported across the membrane after their synthesis is complete. B) are completely translated on free ribosomes in the cytosol. C) begin to cross the membrane while still being synthesized. D) remain within the endoplasmic reticulum.

C) begin to cross the membrane while still being synthesized.

Your friend has just joined a lab that studies vesicle budding from the Golgi and has been given a cell line that does not form mature vesicles. She wants to start designing some experiments but was not listening carefully when she was told about the molecular defect of this cell line. She is too embarrassed to ask and comes to you for help. She does recall that this cell line forms coated pits but vesicle budding and the removal of coat proteins don't happen. Which of the following proteins might be lacking in this cell line? A) clathrin B) Rab C) dynamin D) adaptin

C) dynamin

Researchers often want to isolate a certain type of RNA. For some RNA species, this can be accomplished via affinity chromatography, using beads coated with chains of poly-deoxythymidine (poly-dT). The desired RNA will stick to the beads while unwanted RNAs will flow through the column. The retained RNA can then be eluted. What RNA species can be purified using this method? A) eukaryotic rRNA B) bacterial rRNA C) eukaryotic mRNA D) bacterial mRNA

C) eukaryotic mRNA

The Retinoblastoma (Rb) protein blocks cells from entering the cell cycle by A) phosphorylating Cdk. B) marking cyclins for destruction by proteolysis. C) inhibiting cyclin transcription. D) activating apoptosis.

C) inhibiting cyclin transcription.

During DNA replication, the single-strand DNA-binding (SSB) proteins A) are generally found more on the leading strand than the lagging strand. B) bind cooperatively to single-stranded DNA and cover the bases to prevent base-pairing. C) prevent the folding of the single-stranded DNA. D) bind cooperatively to short hairpin helices that readily form in the single-stranded DNA. E) All of the above.

C) prevent the folding of the single-stranded DNA.

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 mRNA in the mutant cells are normal. Which of the following mutations in the gene for X could explain these results? A) the introduction of a stop codon that truncates protein X at the fourth amino acid B) a change of the first ATG codon to CCA C) the deletion of a sequence that encodes sites at which ubiquitin can be attached to the protein D) a change at a splice site that prevents splicing of the RNA

C) the deletion of a sequence that encodes sites at which ubiquitin can be attached to the protein

Smilin is a (hypothetical) protein that causes people to be happy. It is inactive in many chronically unhappy people. The mRNA isolated from a number of different unhappy individuals in the same family was found to lack an internal stretch of 173 nucleotides that are present in the Smilin mRNA isolated from a control group of generally happy people. The DNA sequence of the Smilin genes from the happy and unhappy people were compared. They differed by just one nucleotide change - and no nucleotides were deleted. Moreover, the change was found in an intron. Which molecular mechanism might explain how a single nucleotide change in a gene could cause the observed internal deletion in the mRNA? A) A mutation at the 5′ end of Intron 1 (I1) causingExon 2 (E2) to be spliced out of the mutant mRNA B) A nonsense mutation in I1 converting an amino acid codon to a stop codon and terminating protein synthesis C) A mutation in E2 converting it from an exon to an intron which is spliced out of the protein. D) A mutation in the 3′ splice site in I1 so that it was no longer recognized by the splicing machinery. Use of the next available 3′ splice site adjacent to E3 would cause the loss of E2 from the mutant mRNA.

D) A mutation in the 3′ splice site in I1 so that it was no longer recognized by the splicing machinery. Use of the next available 3′ splice site adjacent to E3 would cause the loss of E2 from the mutant mRNA.

On average, errors occur in DNA synthesis only once in every ten billion nucleotides incorporated. Which of the following does NOT contribute to this high fidelity of DNA synthesis? A) Complementary base-pairing between the nucleotides B) Exonucleolytic proofreading by the 3′-to-5′ exonuclease activity of the enzyme to correct mispairing even after monomer incorporation C) A strand-directed mismatch repair system that detects and resolves mismatches soon after DNA replication D) All of the above mechanisms DO contribute to the fidelity.

D) All of the above mechanisms DO contribute to the fidelity.

If the genome of the bacterium E. coli requires about 20 minutes to replicate itself, how can the genome of the fruit flyDrosophila be replicated in only 3 minutes? A) The Drosophila genome is smaller than the E. coli genome. B) Eukaryotic DNA polymerase synthesizes DNA at a much faster rate than prokaryotic DNA polymerase. C) The nuclear membrane keeps the Drosophila DNA concentrated in one place in the cell, which increases the rate of polymerization. D) Drosophila DNA contains more origins of replication than E. coli DNA.

D) Drosophila DNA contains more origins of replication than E. coli DNA.

In the following schematic graph of a hypothetical set of RNA-seq data, the number of reads is plotted for a region of chromosome containing two genes, from samples obtained from two different tissues. Which gene (X or Y) do you think is more likely a "housekeeping" gene? Which region (1 or 2) within gene Y most likely corresponds to an exon? A) Gene X; region 1 B) Gene X; region 2 C) Both genes; region 1 D) Gene Y; region 1 E) Gene Y; region 2

D) Gene Y; region 1

Which of the following repair pathways can accurately repair a double-strand break? A) Base excision repair B) Nucleotide excision repair C) Direct chemical reversal D) Homologous recombination E) Nonhomologous end joining

D) Homologous recombination

When scientists were first studying the fluidity of membranes, they did an experiment using hybrid cells. Certain membrane proteins in a human cell and a mouse cell were labeled using antibodies coupled with differently colored fluorescent tags. The two cells were then coaxed into fusing, resulting in the formation of a single, double-sized hybrid cell. Using fluorescence microscopy, the scientists then tracked the distribution of the labeled proteins in the hybrid cell. Which best describes the results they saw and what they ultimately concluded? A) The mouse and human proteins remained confined to the portion of the plasma membrane that derived from their original cell type. This suggests that cells can restrict the movement of their membrane proteins to establish cell-specific functional domains. B) Initially, the mouse and human proteins intermixed, but over time, they were able to resegregate into distinct membrane domains. This suggests that cells can restrict the movement of membrane proteins. C) Initially, the mouse and human proteins were confined to their own halves of the newly formed hybrid cell, but over time, the two sets of proteins recombined such that they all fluoresced with a single, intermediate color. D) Initially, the mouse and human proteins were confined to their own halves of the newly formed hybrid cell, but over time, the two sets of proteins became evenly intermixed over the entire cell surface. This suggests that proteins, like lipids, can move freely within the plane of the bilayer. E) At first, the mouse and human proteins were confined to their own halves of the newly formed hybrid cell, but over time, the two sets of proteins became divided such that half faced the cytosol and half faced the hybrid cell exterior. This suggests that flippases are activated by cell fusion.

D) Initially, the mouse and human proteins were confined to their own halves of the newly formed hybrid cell, but over time, the two sets of proteins became evenly intermixed over the entire cell surface. This suggests that proteins, like lipids, can move freely within the plane of the bilayer.

Integrins are single-pass integral membrane proteins in the plasma membrane of animal cells and are involved in the interaction of the cell with the surrounding extracellular matrix. Which of the following descriptions do you think matches the transmembrane part of an integrin molecule? A) It forms a β barrel. B) It is an α helix that is bent in the middle. C) It is about 10 amino acids long, with every other amino acid side chain being hydrophobic. D) It folds in a conformation with maximal intrachain hydrogen-bonding. E) It is about 100 amino acids long.

D) It folds in a conformation with maximal intrachain hydrogen-bonding.

You are interested in Fuzzy, a soluble protein that functions within the ER lumen. Given that information, which of the following statements must be TRUE? A) Fuzzy has a C-terminal signal sequence that binds to SRP. B) Only one ribosome can be bound to the mRNA encoding Fuzzy during translation. C) Fuzzy must contain a hydrophobic stop-transfer sequence. D) Once the signal sequence from Fuzzy has been cleaved, the signal peptide will be ejected into the ER membrane and degraded.

D) Once the signal sequence from Fuzzy has been cleaved, the signal peptide will be ejected into the ER membrane and degraded.

Upon binding to an extracellular signal, a pair of RTKs dimerize and phosphorylate three tyrosine residues on each other's cytoplasmic tails. These tyrosines serve as docking sites for three intracellular signaling proteins: phosphoinositide 3-kinase (PI 3-K), protein kinase X (PKX), and an adaptor protein (adaptor 1). To determine which tyrosine is recognized by which downstream signaling protein, investigators construct a series of mutant receptor proteins in which the tyrosine residues are replaced, one at a time, with an alanine residue, preventing phosphorylation at that site. The signaling proteins recognized by each of these mutants are identified by co-immunoprecipitation and the effect that the mutations have on the cell's response to the signal is recorded. The results are shown below. Based on the data, what can be concluded about this system? A) PI 3-K is required for the normal cell response. B) Phosphorylated tyrosine 3 serves as a docking site for PKX and PI 3-K. C) PI 3-K can bind to phosphorylated tyrosines 2 or 3. D) Phosphorylated tyrosine 2 serves as a docking site for PKX. E) Adaptor 1 binds to phosphorylated tyrosine 2.

D) Phosphorylated tyrosine 2 serves as a docking site for PKX.

nlike DNA, which typically forms a helical structure, different molecules of RNA can fold into a variety of three- dimensional shapes. This is largely because A) RNA contains uracil and uses ribose as the sugar. B) RNA bases cannot form hydrogen bonds with each other. C) RNA nucleotides use a different chemical linkage between nucleotides compared to DNA. D) RNA is single-stranded.

D) RNA is single-stranded.

Which of the following is true regarding heterochromatin in a typical mammalian cell? A) About 1% of the nuclear genome is packaged in heterochromatin. B) The DNA in heterochromatin contains all of the inactive genes in a cell. C) Genes that are packaged in heterochromatin are permanently turned off. D) The different types of heterochromatin share an especially high degree of compaction. E) Heterochromatin is highly concentrated in the centromeres but not the telomeres.

D) The different types of heterochromatin share an especially high degree of compaction.

Telomeres serve as caps at the ends of linear chromosomes. Which of the following is not true regarding the replication of telomeric sequences? A) The lagging-strand telomeres are not completely replicated by DNA polymerase. B) Telomeres are made of repeating sequences. C) Additional repeated sequences are added to the template strand. D) The leading strand doubles back on itself to form a primer for the lagging strand.

D) The leading strand doubles back on itself to form a primer for the lagging strand.

Mobile DNA elements likely contributed to the evolution of higher organisms by the A) generation of gene families by gene duplication. B) creation of new genes by exon shuffling. C) formation of more complex regulatory regions. D) all of the above

D) all of the above

After isolating the rough endoplasmic reticulum from the rest of the cytoplasm, you purify the RNAs attached to it. Which of the following proteins do you expect the RNA from the rough endoplasmic reticulum to encode? A) soluble secreted proteins B) ER membrane proteins C) plasma membrane proteins D) all of these answers are correct

D) all of these answers are correct

For a nerve cell at its resting potential (-70 mV), the forces acting on potassium ions (K+) are A)none: K+ ions do not move at the resting potential. B)an electrical gradient, pulling K+ inward, and a chemical gradient, pushing K+ inward. C) an electrical gradient, pushing K+ outward, and a chemical gradient, pulling K+ inward. D) an electrical gradient, pulling K+ inward, and a chemical gradient, pushing K+ outward. E) an electrical gradient, pushing K+ outward, and a chemical gradient, pushing K+ outward.

D) an electrical gradient, pulling K+ inward, and a chemical gradient, pushing K+ outward.

You join a laboratory to study muscle function. You decide to inhibit the pumping of Ca2+ into the sarcoplasmic reticulum to determine how excess cytosolic Ca2+ will affect muscle function. Which of the following strategies would be effective in blocking Ca2+ pumping? A) block the hydrolysis of ATP to AMP by the Ca2+ pump B) block binding of ATP to the pump in the lumen of the sarcoplasmic reticulum C) enhance the binding of ATP to the Ca2+ pump D) block the phosphorylation of the conserved aspartate in the Ca2+ pump

D) block the phosphorylation of the conserved aspartate in the Ca2+ pump

Levels of Cdk activity change during the cell cycle, in part because A) the Cdks phosphorylate each other. B) the Cdks activate the cyclins. C) Cdk degradation precedes entry into the next phase of the cell cycle. D) cyclin levels change during the cycle.

D) cyclin levels change during the cycle.

Insulin is synthesized in the form of a precursor protein that requires cleavage of two different peptide segments before the matureprotein is secreted from β cells in the pancreas. The first peptide is removed when the protein enters the lumen of the ER. To find out when the second cleavage event takes place, investigators prepare a pair of antibodies: one recognizes the pro-insulin precursor, the other the mature insulin protein. They tag the antibody that binds to the precursor protein with a red fluorescent marker; the antibody that binds to mature insulin is tagged with a green fluorescent marker. When both markers are present, the sample fluoresces yellow.The investigators then incubate an isolated β cell with both antibodies at the same time and monitor the fluorescence in its various membrane-bound compartments. The data are shown in the table below. Based on these observations, where is the second peptide removed from the pro-insulin precursor protein? A) ER B) mature secretory vesicles C) lysosomes D) immature secretory vesicles E) Golgi apparatus

D) immature secretory vesicles

If you were to put the following events in the most likely order of how life might have emerged on Earth, what would be the most likely sequence order (earliest to latest)? A. polymers formed B. protobionts emerged C. metabolism & self-replication D. monomers formed

D, A, B, C

A hungry yeast cell lands in a vat of grape juice and begins to feast on the sugars there, producing carbon dioxide and ethanol in the process: C6H12O6 + 2ADP + 2Pi + H+ → 2CO2 + 2CH3CH2OH + 2ATP + 2H2O Unfortunately, the grape juice is contaminated with proteases that attack some of the transport proteins in the yeast cell membrane, and the yeast cell dies. Which of the following is the most likely cause of the yeast cell's demise? A) toxic buildup of carbon dioxide inside the cell B) toxic buildup of ethanol inside the cell C) diffusion of ATP out of the cell D) inability to import sugar into the cell

D) inability to import sugar into the cell

The G1 DNA damage checkpoint A) causes cells to proceed through S phase more quickly. B) involves the degradation of p53. C) is activated by errors caused during DNA replication. D) involves the inhibition of cyclin-Cdk complexes by p21.

D) involves the inhibition of cyclin-Cdk complexes by p21.

What part of the DNA replication process would be most directly affected if a strain of bacteria lacking the exonuclease activity of DNA polymerase to remove ribonucleotides were used to make the cell extracts? A) initiation of DNA synthesis B) Okazaki fragment synthesis C) leading-strand elongation D) lagging-strand completion

D) lagging-strand completion

Glycolipids and glycoproteins are especially abundant in the A) nucleus. B) mitochondrial inner membrane. C) cytosol. D) plasma membrane.

D) plasma membrane.

What makes it possible for a combination of signal molecules to evoke a response that differs from the sum of the effects that each signal could trigger on its own? A) the ability of different receptors to activate different intracellular relay systems B) the tendency of different cells to display different receptors C) the ability of different signal molecules to bind to the same receptor D) the ability of different intracellular relay systems to interact E) the ability of the same signal molecule to bind to different receptors

D) the ability of different intracellular relay systems to interact

Proteins that are fully translated in the cytosol do not end up in A) the cytosol. B) the mitochondria. C) the interior of the nucleus. D) transport vesicles.

D) transport vesicles.

Each of the following is an activity of a microtubule motor protein during mitosis except A) shortening kinetochore microtubules. B) pulling kinetochore microtubules in at centrosomes. C) pushing interpolar microtubules for anaphase B. D) pulling astral microtubules toward the cell cortex. E) All of the above are activities of microtubule motors.

E) All of the above are activities of microtubule motors.

Consider the following image of multiple genes (a and b) on a chromosome . Based on the figure, which of these statements is/are correct? A) For different genes, opposite strands of DNA can serve as a template. B) The template strand is always read by RNA polymerase in the 5'-to-3' direction. C) RNA is always polymerized in the 5'-to-3' direction. D) The gene promoter is always downstream of the transcription start site. E) Both A and C

E) Both A and C

Most fish genomes are at least 1 billion nucleotide pairs long. However, the genome of the puffer fish Fugu rubripes is quite small at only about 0.4 billion nucleotide pairs, even though the number of Fugu genes is estimated to be comparable to that of its relatives which have larger genomes. What do you think mainly accounts for the Fugu genome being this small? A) Evolutionary advantage of extremely small exon sizes in the Fugu lineage B) Unusual disappearance of all intronic sequences from the Fugu genome C) Increased abundance of transposable elements in the Fugu genome D) Increased occurrence of mitotic whole-chromosome loss in the Fugu lineage E) Low relative rate of DNA addition compared to DNA loss in the Fugu lineage

E) Low relative rate of DNA addition compared to DNA loss in the Fugu lineage

Consider the following image depicting a prokaryotic gene and a eukaryotic gene. Which of the following statements is supported by the information in this image and is consistent with your knowledge regarding genomic architecture in prokaryotes and eukaryotes? A) The prokaryotic cell must have a nuclear spliceosome to remove introns from DNA. B) The eukaryotic cell must have a nuclear spliceosome to remove introns from DNA. C) The prokaryotic cell must have a cytoplasmic spliceosome to remove introns from RNA. D) The eukaryotic cell must have a cytoplasmic spliceosome to remove introns from RNA. E) The eukaryotic cell must have a nuclear spliceosome to remove introns from RNA.

E) The eukaryotic cell must have a nuclear spliceosome to remove introns from RNA.

Compared to the human genome, the genome of yeast typically has A) more repetitive DNA. B) longer genes. C) more introns. D) longer chromosomes. E) a higher fraction of coding DNA.

E) a higher fraction of coding DNA.

The nuclear DNA polymerases in human cells A) polymerize about 1000 nucleotides per second during DNA replication in vivo. B) are incapable of 3′-to-5′ exonuclease activity. C) are capable of 3′-to-5′ DNA polymerase activity. D) have a single active site that is used for both polymerization and editing. E) are unable to initiate polymerization de novo (i.e. in the absence of a primer).

E) are unable to initiate polymerization de novo (i.e. in the absence of a primer).

Due to their high transcription rate, active ribosomal RNA (rRNA) genes can be easily distinguished in electron micrographs of chromatin spreads. They have a characteristic "Christmas tree" appearance, where the DNA template is the "trunk" of the tree and the nascent RNA transcripts form closely packed "branches." At the base of each branch is an RNA polymerase extending that branch, while RNA processing complexes at the tip of the branch form terminal "ornaments." The top of the tree represents the ... of the rRNA gene, and the "ornaments" are at the ... end of the nascent rRNA molecules. A) end; 3' B) end; 5' C) beginning; either 3' or 5' D) beginning; 3' E) beginning; 5'

E) beginning; 5'

he copy number of some human genes, such as the salivary amylase gene AMY1, varies greatly between different individuals. The salivary amylase breaks down some of the dietary starch into smaller sugars. In the case of AMY1, a positive correlation has been observed between the copy number and the amount of amylase in the saliva. Gene copy number per diploid genome can be estimated by performing a quantitative polymerase chain reaction (PCR) using primers specific to the gene of interest. You have performed such PCR experiments on samples from two human populations that have traditional diets with low and high starch levels, respectively, and have plotted the data in the histogram below. Which population (A or B) in the histogram is likely to be the one with traditionally higher dietary starch?

Population B

Carl Woese used which of the following cellular molecules to determine the highest order of biological taxonomic rank, Domains? a) DNA b) ribosomal RNA c) ribozymes d) viruses e) none of these is a best choice

b) ribosomal RNA

The methanogens (prokaryotes that produce methane) belong to which biological Domain? a) Domain Bacteria b) Domain Archaea c) Domain Eukarya d) Domain Fungi e) Domain Animalia

b) Domain Archaea

The individual who won the 1958 Nobel Prize for 1stdetermination of a protein structure (insulin) was? a) Linus Pauling b) Frederick Sanger c) J. Craig Venter d) George Palade e) none of these

b) Frederick Sanger

The first Human cells successfully grown in culture were? a) brain cell neurons b) HeLa cells c) epithelial cells of Human kidney d) filopodia e) none of these is a correct choice

b) HeLa cells

The figure to the right likely depicts which of the following? a) a quaternary level protein structure b) a beta barrel motif c) a Zn-finger d) a serine protease e) none of these is correct

b) a beta barrel motif

Mycoplasma capricolumhas had its genome (chromosome) replaced with? a) a native yeast genome b) a synthetic chromosome of Mycoplasma mycoides c) bacteriorhodopsin d) tabacco mosaic virus (TMV) e) none of these is correct

b) a synthetic chromosome of Mycoplasma mycoides

The type of inhibition being shown by inhibitor-1 is a) irreversible b) competitive c) non-competitive d) choose this answer if none of these is a best choice

b) competitive

Which of the following statements about the oxidation of fatty acids is correct? a) fatty acid oxidation generates increased net amounts of CO2 b) converts free fatty acid into acetyl-CoA c) fatty acids are oxidized in the chloroplasm d) fatty acid oxidation makes ATP in the cytoplasm of the cell e) choose this answer if none of these is correct

b) converts free fatty acid into acetyl-CoA

An unfavorable reaction (has a positive +DG) can be driven to occur by? a) increasing its +DG b) coupling it to a reaction with a -DG c) only altering the temperature d) one cannot get an unfavorable reaction to ever occur e) none of these is correct

b) coupling it to a reaction with a -DG

In which of the following procedures of electron microscopy are sample specimens treated with liquid nitrogen (-335f0C) and then fractured with a microtome knife? a) transmission electron microscopy b) cryoelectron microscopy c) scanning electron microscopy d) autoradiography e) immunofluorescence microscopy

b) cryoelectron microscopy

Experiment comparing gene locations within a nucleus of nocturnal and diurnal animals indicated that bundles of similar gene clusters occupy the exact same locales? a) true b) false

b) false

The tendency of nonpolar molecules to aggregate in aqueous solution is due to their? a) hydrophilicity b) hydrophobicity c) charge d) van der Waal's attraction e) none of these is correct

b) hydrophobicity

A peptide bond? a) allow free rotation about the bond b) is planar c) forms via hydrolysis d) links two amino groups together e) none of these is correct

b) is planar

In an attempt to determine the minimal number of genes a cell would need to be that cell Craig Venter used a RISC (RNA Induced Silencing Complex) to reduce or inactivate the activity of? a) ribozymes b) mRNA c) DNA d) protein motifs e) none of these is a correct choice

b) mRNA

It is possible that the architectural principle of tensegrity applies within cells via which of the following proteins? a) enzymes b) microtubules and microfilaments c) storage proteins d) kinesin proteins e) none of these is correct

b) microtubules and microfilaments

In a known enzymatic pathway, the conversion of A àB has a ΔG0' of +3.6 Kcal/mol and the conversion of B àC has a ΔG0' of -7.3Kcal/mol. The overall free energy change for the AàBàC coupled reaction is? a) +3.7 Kcal/mol b) -10.9 Kcal/mol c) -3.7Kcal/mol d) -7.3 Kcal/mol e) none of these is the best choice

c) -3.7Kcal/mol

The initial molecules containing 14C after exposure to 14CO2of C3 and C4 plant photosynthesis are, respectfully? a) ribulose 1,5-bisphosphate & malic acid b) malate & carbon dioxide c) 3-phosphoglycerate & oxaloacetic acid d) glucose & fructose e) none of these pairs

c) 3-phosphoglycerate & oxaloacetic acid

Which of the following would be an example of multi-enzyme complex? a) myoglobin b) lysozyme c) ATP synthase d) ubiquitin e) none of these is correct

c) ATP synthase

Which of the following organisms is most likely to have the greatest problem with photorespiration? a) C4 plants b) heterotrophs c) C3 plants d) CAM plants e) none of these bacteria

c) C3 plants

Which of the following products is produced directly by the action of pyruvate dehydrogenase? a) ATP b) FADH2 c) CO2 d) cytoplasmic NADH e) none of these is correct

c) CO2

The first "cells" were observed by? a) Matthias Schleiden b) Leeuwenhoek c) Robert Hooke d) Charles Darwin e) Daniel DiResta

c) Robert Hooke

The Biogenic Law ("All living cells arise from preexisting cells") was first espoused by? a) Charles Darwin b) Theodor Schwann c) Rudolph Virchow d) Craig Venter e) Dan DiResta

c) Rudolph Virchow

The 18-19thcentury scientific thought that the Nature of Life was the result of a force peculiar to livingorganisms only was known as? a) Mechanism b) Systemism c) Vitalism d) Cell Biologism e) none of these is correct

c) Vitalism

Functional group that has acid properties & is often found in cells in ionized forms with a charge of -1 ? a) a ketone b) a methyl group c) a carboxyl group d) an amino group e) none of these

c) a carboxyl group

The instrument used to cut extremely thin section of biological samples is? a) a compound lens system b) the condenser c) a microtome d) the focal plane e) none of these is a correct choice

c) a microtome

To section biological specimens for microscopy one would most likely use? a) autoradiography b) green fluorescent protein c) a microtome d) a centrifuge e) none of these would be used

c) a microtome

The molecular system that forms a peptide bond during cellular protein synthesis is a? a) DNA molecule b) an enzymatic protein c) a ribozyme d) viroid e) none of these is correct

c) a ribozyme

During cell respiration and photosynthesis CO2is released during which of these processes? a) non-cyclic photophosphorylation b) Calvin cycle c) alcoholic fermentation d) lactic acid fermentation e) none of these is a correct choice

c) alcoholic fermentation

The cell biology procedure that uses photographic emulsion placed over microscopy specimens to reveal the location of radioactive molecules in cells labeled with radioactive tags is known as? a) isoelectric focusing b) immune fluorescent microscopy c) autoradiography d) X-ray crystallography e) known of these is correct

c) autoradiography

Nucleotides made abiotically under early Earth conditions might have been concentrated by interaction? a) with asteroids b) with vast volumes of water c) between microscopic layers of clay d) with methane e) none of these is a correct choice

c) between microscopic layers of clay

The chemical functional group that has acidic properties and is found in cells mostly in its ionized form with a charge of -1 is the? a) amino group, as in amino acids b) carbonyl group as in ketones c) carboxyl as in glycine d) methyl group as in methane e) the hydroxyl group as in ethyl alcohol

c) carboxyl as in glycine

The type of light microscopy that uses beams of polarized light and produces images that look as if a sample cell is casting a 3D shadow is? a) bright-filed microscopy b) phase-contrast microscopy c) differential interference-contrast microscopy d) stained bright-field microscopy e) none of these

c) differential interference-contrast microscopy

An emergent property is most likely? a) random reactions which release energy from stored carbon compounds b) only endergonic reactions which expend energy driving other reactions c) reactions that use energy from the environment to synthesize cellular polymers d) unexpected, non-trivial properties of simpler components that are from complexity e) none of these is a best choice

d) unexpected, non-trivial properties of simpler components that are from complexity

The Michaelis constant for the Inhibitor-2reaction is? a) 0.6mg/min glucose b) 4.0uM G-6-phosphate c) 12mg/min glucose d) 0.6uM G-6-phosphate e) choose this answer if none of these is a best choice

d) 0.6uM G-6-phosphate

Two short alpha helices connected by a loop around a Ca ion binder is known as a(n)? a) a leucine zipper motif b) zinc finger motif c) CAP domain d) EF hand (helix-turn-helix) motif e) none of these

d) EF hand (helix-turn-helix) motif

Which of the following chemical bonds requires the greatest energy to break? a) an ionic bond b) a hydrogen bond c) a van der Waal's attraction d) a carbon-carbon single bond e) hydrophobic interaction

d) a carbon-carbon single bond

A graduate student in microscopy is perplexed for his fluorescently stained cells appear fuzzy and somewhat out of focus when viewed in the lab's fluorescent microscope. His major professor recommends that he should use which of the following microscopes to improvement the resolution and the plane of focus in his fluorescently stained cells? a) a scanning electron microscope b) a transmission electron microscope c) autoradiography d) a confocal fluorescent microscope e) a microtome

d) a confocal fluorescent microscope

Which of the following is not a 'universal' characteristic all living cells? a) templated polymerization b) templated transcription c) an RNA-based genetic code d) a free energy status that is at chemical equilibrium e) all of these are universal to living cells

d) a free energy status that is at chemical equilibrium

Rubisco (ribulose 1,5-biphospahe carboxylase-oxygenase)? a) catalyzes the carboxylation of CO2to ribulose 1,5-bisphosphate b) can initiate photorespiration when the O2/CO2ratio is high c) makes up as much as 50% of total leaf proteins d) all of the above (a-c) e) a and b, but not c

d) all of the above (a-c)

The volcanic laboratory experiments performed by Stanley Miller were able to synthesize which of the following biomolecules? a) DNA b) RNA c) lipids d) amino acids e) it made all of these molecules readily

d) amino acids

Reduction of FAD to FADH2occurs in? a) glycolysis b) Krebs cycle c) fatty acid oxidation d) b and c only e) in a, b, and c

d) b and c only

Lithotrophy can employ ________ to provide the energy for biological energy transformations? a) oxidation of food molecules, as glucose b) light photons c) only heat energy d) chemical electron donors as H2S and H2 e) none of these is correct

d) chemical electron donors as H2S and H2

Proteins are commonly classified by their functions rather than structure. The protein class of actins are best classified as ______ proteins? a) enzyme b) storage c) defensive d) contractile e) none of these is a proper classification of the actins

d) contractile

Given what you know about the differences between prokaryotic cells and eukaryotic cells, which of the following processes would you study using the model organism of E. coli? a) formation of the endoplasmic reticulum b) development of sexual cell cycles c) how the actin contributes to muscle cell contraction d) how cells decode their genetic instructions to make proteins e) how mitochondria get distributed to cells during cell division

d) how cells decode their genetic instructions to make proteins

During cellular respiration the oxidative phosphorylation process protons accumulate? a) in inner thylakoid disk space b) in the mitoplasm c) in the chloroplasm d) in the peri-mitochondrial space e) choose this answer if none of these is correct

d) in the peri-mitochondrial space

Energy in cells is found? a) in concentration gradients across biological membranes b) in the chemical bonds of biological molecules c) in electrical gradients across membranes d) it is found in all of the above

d) it is found in all of the above

The pH at which an amino acid has no net charge is? a) pH 7.0 b) an acid pH c) a basic pH d) its isoelectric point e) none of these

d) its isoelectric point

The cellular respiration reaction shown to the right is which of the following types of reactions? a) decarboxylation b) oxidation-reduction c) fermentation d) substrate level phosphorylation e) none of these is correct

d) substrate level phosphorylation

The construction of fully functional cells or parts of cells from scratch (abiotically) is referred to as? a) astrobiology b) proteomics c) volcanic syntheses d) synthetic biology e) none of these is correct

d) synthetic biology

The differential staining of bacteria into Gram+ and Gram- stained samples is due to which of the following structural component of the bacteria? a) their DNA b) their RNAs c) their size d) the makeup of their cell wall components e) none of these is a best choice

d) the makeup of their cell wall components

A new compound is isolated from chloroplast thylakoid membranes and is claimed to be a previously unrecognized carrier in the photosynthetic ETC and is given the name DiRestachrome. Which of the following lines of evidence do you fell might provide support to assigning DiRestachrome a position within the photosynthetic ETC? a) removal of DiRestachrome from these membranes results in an increased rate of CO2consumption b) oxidation of DiRestatchrome results in a release of protons from crista membranes c) rates of oxidation-reduction of DiRestachrome are identical to rates of NAD+/NADH in fermentations d) DiRestachromome has a redox potential between that of NADH/NAD+ couple and FAD/FADH2 e) choose this answer if none of these support the hypothesis that DiRestachrome as a new carrier

e) choose this answer if none of these support the hypothesis that DiRestachrome as a new carrier

Cell and molecular biology often includes aspects from all of the following biological disciplines except? a) biochemistry b) molecular genetics c) development biology d) neurobiology e) chose this answer if it includes aspects from all of these disciplines

e) chose this answer if it includes aspects from all of these disciplines

Conformers are? a) proteins with identical amino acid sequences, but different catalytic activity b) proteins with identical conformation shapes c) proteins with only alpha helical structure d) proteins with only beta sheet structure e) none of these is a correct choice

e) none of these is a correct choice

Concerning glycolysis? a) it occurs in the mitoplasm b) it decarboxylates pyruvate c) it requires O2 d) it makes ATP via oxidative phosphorylation e) none of these is correct

e) none of these is correct

The Shuttles commonly used by highly metabolic cells during aerobic cellular respiration? a) move pyruvate into the mitochondria b) shuttle acetyl-CoA into the cytoplasm c) reduce CO2 into sugar d) transfers acetyl-CoA across the inner mitochondrial membrane e) none of these is correct

e) none of these is correct

Oxidative phosphorylation and photosynthetic phosphorylation appear generally similar processes, both consisting of ATP synthesis coupled to the transfer of electrons along an electron carrier chain, however oxidative phosphorylation? a) uses of water as the terminal electron acceptor b) uses the porins proteins of thylakoids c) uses pyruvate dehydrogenase to generate FADH2 d) uses cytochromes in its electron chain e) none of these processes are correct concerning oxidative phosphorylation

e) none of these processes are correct concerning oxidative phosphorylation

Which of the following clues would distinguish a cell as prokaryotic from eukaryotic? a) presence of a cell membrane b) presence of ribosome c) presence of DNA d) metabolic reactions e) none of these traits would distinguish a cell as distinct from eukaryotic cells

e) none of these traits would distinguish a cell as distinct from eukaryotic cells