UMKC Cell Bio Unit 2

Which of the following produces transport vesicles for both exocytosis and endocytosis pathways? a) The endoplasmic reticulum b) The Golgi apparatus c) The endosome d) The plasma membrane e) None of the above.

b) The Golgi apparatus

In the spicing reaction, the 2' OH of an A in the intron reacts with a ribonucleotide at the __ to form a lariat structure. a) 5' end of the intron b) 3' end of the intron c) 5' end of an upstream exon d) 3' end of a downstream exon e) 5' end of a downstream exon

a) 5' end of the intron

What binds to a nuclear localization signal in the sequence of a nuclear protein during nuclear transport of this protein from the cytosol to the nucleus? a) A nuclear import receptor (an importin) b) A nuclear import receptor (importin) bound to Ran-GTP c) A nuclear import receptor (importin) bound to Ran-GDP d) The nuclear pore complex proteins e) None of the above bind to the nuclear localization signal.

a) A nuclear import receptor (an importin)

What type of DNA is found in the nucleolus? a) DNA encoding ribosomal RNA b) DNA encoding ribosomal proteins c) DNA encoding nuclear pore complexes d) DNA encoding both ribosomal RNA and ribosomal proteins. e) DNA encoding telomerase

a) DNA encoding ribosomal RNA

Proteins which aggregate a) In the ER are targeted for degradation, but in the Golgi are targeted for regulated secretion. b) In the ER are targeted for regulated secretion, but in the Golgi are targeted for degradation. c) In both the ER and Golgi are targeted for regulated secretion. d) In both the ER and Golgi are targeted for degradation.

a) In the ER are targeted for degradation, but in the Golgi are targeted for regulated secretion.

What does telomerase synthesize? a) It extends the 3' end of the template strand for lagging strand synthesis at the end of chromosomes. b) It extends the 5' end of the template strand for lagging strand synthesis at the end of chromosomes. c) It extends the 3' end of the lagging strand at the end of chromosomes. d) It extends the 5' end of the lagging strand at the end of chromosomes, e) It extends the 3' end of the leading strand at the end of chromosomes.

a) It extends the 3' end of the template strand for lagging strand synthesis at the end of chromosomes.

The signal that directs proteins back to the endoplasmic reticulum from the Golgi apparatus is a) KDEL b) mannose 6 phosphate. c) ubiquitin. d) an N-terminal cleaved signal peptide. e) COPII.

a) KDEL

After reaching the endosome during endocytosis, what typically happens to the proteins involved in this process? a) Receptor proteins from the plasma membrane can be returned to the plasma membrane, cargo proteins are eventually degraded in the lysosome, and the mannose 6 phosphate receptor is returned to the Golgi apparatus. b) Mannose 6 phosphate receptors are transported to the plasma membrane, cargo proteins are eventually degraded in the lysosome, and the receptors taken up at the plasma membrane are transported to the plasma Golgi apparatus. c) Cargo proteins taken up at the plasma membrane can be returned to the plasma membrane, receptor proteins from the plasma membrane are eventually degraded in the lysosome, and the mannose 6 phosphate receptor is returned to the Golgi apparatus. d) Cargo proteins taken up at the plasma membrane can be returned to the plasma membrane, mannose 6 phosphate receptor proteins are eventually degraded in the lysosome, and receptor proteins taken up at the plasma membrane are transported to the Golgi apparatus. e) Receptor proteins taken up at the plasma membrane can be returned to the plasma membrane, mannose 6 phosphate receptor proteins are eventually degraded in the lysosome, and cargo proteins taken up at the plasma membrane are transported to the Golgi apparatus.

a) Receptor proteins from the plasma membrane can be returned to the plasma membrane, cargo proteins are eventually degraded in the lysosome, and the mannose 6 phosphate receptor is returned to the Golgi apparatus.

Which of the following events during production of endocytic vesicles from the plasma membrane is produced only by the inherent properties of membrane phospholipids, rather than by the actions of proteins? a) Sealing of the plasma membrane after scission of the vesicle b) Formation of the endocytic buds at the plasma membrane c) Selection of membrane-bound cargo proteins d) Scission (cutting off) of the vesicles from the membrane surface e) All of the above (A, B, C and D) are produced only by the inherent properties of membrane lipids.

a) Sealing of the plasma membrane after scission of the vesicle

You have generated two sets of vesicles, one with bacteriorhodopsin (which pumps protons out of bacteria in response to light) and the mitochondrial F1 ATPase inserted into the membranes of the vesicles, and the other with only the F1 ATPase. In both cases, the parts of the proteins that normally face the outside of the cell or the mitochondrial intermembrane space are inside the vesicles, and protons, ADP and inorganic phosphate are outside the vesicles. How will both sets of vesicles respond to illumination with light? a) The vesicles with bacteriorhodopsin will exhibit a net accumulation of protons in the vesicle and will generate ATP outside the vesicle, while the other set of vesicles will not accumulate protons in the vesicle and ATP outside the vesicle. b) Both will exhibit a net accumulation of protons inside the vesicle and ATP outside the vesicle. c) Neither will exhibit a net accumulation of protons inside the vesicle and ATP outside the vesicle. d) The vesicles with bacteriorhodopsin will exhibit a net accumulation of protons in the vesicle but will not generate ATP outside the vesicle, while the other set of vesicles will not accumulate protons in the vesicle but will generate ATP outside the vesicle. e) The vesicles with bacteriorhodopsin will exhibit a net accumulation of protons in the vesicle but will not generate ATP outside the vesicle, while the other set of vesicles will not accumulate protons in the vesicle and will not generate ATP outside the vesicle.

a) The vesicles with bacteriorhodopsin will exhibit a net accumulation of protons in the vesicle and will generate ATP outside the vesicle, while the other set of vesicles will not accumulate protons in the vesicle and ATP outside the vesicle.

You have constructed phospholipid vesicles that contain Na+/K+ pumps as the sole membrane protein. The portion of the pump that normally faces the cytosol is oriented towards the outside of the vesicles. The solutions inside the vesicles and outside the vesicles have only Na+ ions but NO K+ ions, and ATP is present only on the outside of the vesicle. What would happen? a) Very little Na+ would move inside the vesicle (only one partial cycle of all the pumps would occur, moving a single cycle of Na+ to the inside of the vesicle) b) Very little Na+ would move outside the vesicle (only one partial cycle of all the pumps would occur, moving a single cycle of Na+ to the outside of the vesicle). c) Na+ would be pumped repeatedly out of the vesicle. d) Na+ would be pumped repeatedly into the vesicle. e) No Na+ at all would move.

a) Very little Na+ would move inside the vesicle (only one partial cycle of all the pumps would occur, moving a single cycle of Na+ to the inside of the vesicle)

A transmembrane protein has two binding sites - one for solute A and one for solute B. Either both sites are exposed on one side of the membrane, or both sites are exposed on the other side of the membrane. The protein can switch between these two conformational states only if both binding sites are occupied or if both binding sites are empty, but it cannot switch if only one binding site is occupied. The protein is a) a symport carrier protein. b) an antiport carrier protein. c) an antiport channel protein. d) an symport channel protein. e) the Na+/K+ ATPase

a) a symport carrier protein.

Which of the following modifications does NOT occur in the lumen of the ER? a) addition of a sugar residue to dolichol phosphate b) addition of a branched sugar chain to the amino acid asparagine c) rearrangements of disulfide bonds d) addition of GPI anchors to proteins e) All of the above occur in the lumen of the ER.

a) addition of a sugar residue to dolichol phosphate

A transmembrane protein has two binding sites - one for solute A and one for solute B. Either both sites are exposed on one side of the membrane, or both sites are exposed on the other side of the membrane. The protein can switch between these two conformational states only if one binding site is occupied, but not if both binding sites are occupied or if both binding sites are empty. The protein is a) an antiport carrier protein b) an symport carrier protein c) an antiport channel protein d) an symport channel protein

a) an antiport carrier protein

A transmembrane protein has two binding sites - one for solute A and one for solute B. Either both sites are exposed on one side of the membrane, or both sites are exposed on the other side of the membrane. The protein can switch between these two conformational states only if one binding site is occupied but not if both binding sites are occupied or if both binding sites are empty.The protein is a) an antiport carrier protein. b) a symport carrier protein. c) an antiport channel protein. d) a symport channel protein. e) a K+ leak channel.

a) an antiport carrier protein.

The phase of mitosis during which replicated chromosomes are separated into separate chromatids by microtubules attached to both chromatids, thereby moving them to each pole of the cell is a) anaphase. b) prophase. c) telophase. d) interphase e) metaphase.

a) anaphase.

In either of these models for evolution of the nucleus, the layer of the outer nuclear membrane that lies inside the nuclear envelope evolved from a layer that was originally a) on the extracellular side of the plasma membrane. b) on the cytosolic side of the plasma membrane. c) on the cytosolic side of the endoplasmic reticulum d) on the mitochondrial membrane e) in the liver

a) on the extracellular side of the plasma membrane.

The electron donor with the highest (most positive) redox potential during electron transport for the photosynthesis light reactions is a) water b) P680 reduced c) P700 oxidized d) P700 reduced e) NADPH

a) water

What causes a voltage-gated Ca++ channel to open, thereby signaling neurotransmitter release? a) A neurotransmitter b) A change in membrane potential from a negative to a more positive value. c) A change in membrane potential from a positive to a more negative value d) An influx of Ca++ e) An efflux of Ca++

b) A change in membrane potential from a negative to a more positive value.

Which one of the following is a FALSE statement? a) Channels can produce passive transport. b) Channels can produce active transport. c) Carriers must change conformation to transport ions from one side of the membrane to the other. d) Carriers can produce passive transport. e) Carriers can produce active transport.

b) Channels can produce active transport.

Which of the following would NOT happen in a cell? a) Channels produce passive transport. b) Channels produce active transport. c) Carrier proteins produce active transport. d) Carrier proteins produce passive transport. e) Channels change conformation

b) Channels produce active transport.

Coated vesicles can be formed in vitro when adaptins, coat proteins and dynamin-GTP are added to eukaryotic plasma membrane fragments. What would happen if you left adaptins out of the in vitro reaction but included the other components? a) Clathrin coats would assemble around patches of membrane and form buds, but there would be no cargo receptors in the buds. b) Clathrin coats would not assemble around patches of membrane and buds would not form. c) Clathrin coats would not assemble around patches of membrane, but budded vesicles would form with cargo receptors present, and these uncoated vesicles would be released from the membrane. d) Clathrin coats would not assemble around patches of membrane, but budded vesicles would form with cargo receptors present, although these uncoated vesicles would not be released from the membrane. e) Normally formed clathrin-coated vesicles would be released from the membrane (i.e., there would be no effect of omitting adpatins).

b) Clathrin coats would not assemble around patches of membrane and buds would not form.

Which of the following is NOT a component of the DNA polymerase complex at the replication fork? a) DNA polymerase b) DNA ligase c) a sliding clamp d) the helicase e) the primase

b) DNA ligase

During translation, proofreading (e.g., proceeding only if the correct tRNA is bound with the mRNA codon) occurs when a) the peptide bond is synthesized by peptidyl transferase b) GTP is cleaved by EF-Tu. c) EF-G-GTP binds the ribosome. d) the large ribosomal subunit moves forward. e) the tRNA is released from the E site.

b) GTP is cleaved by EF-Tu.

What evolutionary advantage is offered by the mRNA splicing reaction? a) It allows primary transcripts prior to splicing to encode full proteins without any interruptions in the protein sequence. b) It allows multiple proteins with somewhat different sequences to be encoded by a single gene. c) It produces the methyl guanosine cap that directs translation. d) It produces the poly A tails for mRNAs. e) Introns are always the part of the mRNA in which transcriptional termination occurs.

b) It allows multiple proteins with somewhat different sequences to be encoded by a single gene.

Which of the following is TRUE about ion concentrations at resting membrane potential? a) Na+ concentration is typically higher inside the cell. b) K+ concentration is typically higher inside the cell. c) Cl- concentration is typically higher inside the cell. d) Ca++ is typically higher in the cytosol than in the endomembrane system under non-signaling conditions. e) None of the above are true.

b) K+ concentration is typically higher inside the cell.

A newly replicated DNA strand in a replication bubble with two forks is a) Leading strand or lagging strand (not both). b) Leading strand on one side of the bubble and lagging strand on the other side

b) Leading strand on one side of the bubble and lagging strand on the other side

Predict the membrane orientation in the endoplasmic reticulum (ER) of a protein that is synthesized with an internal ER anchor sequence (not cleaved off) , followed by a stop-transfer sequence and then a start transfer sequence in more C terminal regions of the protein (with no more stop transfer sequences in the most C terminal region). Going from the N terminus to the C terminus, the orientation would be: a) N terminal end in the lumen, transmembrane segment, C terminal end in the cytosol. b) N terminal end in the cytosol, transmembrane segment, loop in the lumen, transmembrane segment, loop in the cytosol, transmembrane segment, C terminal end in the lumen. c) N terminal end in the lumen, transmembrane segment, loop in the cytosol, transmembrane segment, C terminal end in the lumen d) N terminal end in the cytosol, transmembrane segment, C terminal end in the lumen. e) N terminal end in the cytosol, transmembrane segment, loop in the lumen, transmembrane segment, loop in the cytosol, transmembrane segment, loop in the lumen, transmembrane segment

b) N terminal end in the cytosol, transmembrane segment, loop in the lumen, transmembrane segment, loop in the cytosol, transmembrane segment, C terminal end in the lumen.

Place the electron transport carriers in order for the mitochondrial electron transport, from the one with lowest redox potential (most tendency to give up electrons; first) to the one with the highest redox potential (least tendency to give up electrons; last) a) NADH-coenzyme Q oxidoreductase, Cytochrome C oxidase, Coenzyme Q-cytochrome C oxidoreductase b) NADH-coenzyme Q oxidoreductase, Coenzyme Q-cytochrome C oxidoreductase, Cytochrome C oxidase c) Coenzyme Q-cytochrome C oxidoreductase, Cytochrome C oxidase, NADH-coenzyme Q oxidoreductase d) Coenzyme Q-cytochrome C oxidoreductase, NADH-coenzyme Q oxidoreductase, Cytochrome C oxidase e) Cytochrome C oxidase, Coenzyme Q-cytochrome C oxidoreductase, NADH-coenzyme Q oxidoreductase

b) NADH-coenzyme Q oxidoreductase, Coenzyme Q-cytochrome C oxidoreductase, Cytochrome C oxidase

For which of the following ions is the electrochemical gradient (combination of concentration and electrical gradients) across the plasma membrane typically the largest at resting membrane potential in an animal cell? a) K+ b) Na+ c) Cl- d) The gradients for Na+ and K+ are equally large. e) The gradients for Na+ and Cl- are equally large.

b) Na+

During the action potential, membrane depolarization (positive potential) is produced by movement of ____(1) from the extracellular fluid to the cytosol, while rapid membrane repolarization is produced by movement of ___(2) ions from the cytosol to the extracellular fluid. a) Na+ (1), Na+(2) b) Na+(1),K+(2) c) Na+(1),Cl-(2) d) K+(1), Na+ (2) e) K+(1), K+ (2)

b) Na+(1),K+(2)

The protein that binds first to the TATA box to initiate the assembly of the basal transcription complex is a) TFIIA. b) TFIID. c) RNApolymeraseII. d) TFIIH. e) PABP.

b) TFIID.

DNA can be replicated in a test tube containing a mixture that includes DNA template strands and deoxyribonucleotides, Modified versions of deoxyribonucleotides can be added that lack a hydroxyl group at the 3' carbon and instead contain two hydrogen atoms at this carbon. What would be the effect of these "dideoxyribonucleotides" on DNA synthesis? a) The dideoxyribonucleotides would not be incorporated into DNA by any of the DNA replication enzymes. b) The dideoxyribounucleotides would be incorporated into newly synthesized DNA by DNA polymerase but would terminate further elongation of the DNA strand when so incorporated. c) The dideoxyribounucleotides would be incorporated into the DNA by DNA polymerase and serve as sites for elongation of the synthesized strand (just like normal deoxyribonucleotides). d) The dideoxyribonucleotides could be incorporated into the DNA by DNA polymerase but could not be excised by the 3' to 5' exonuclease activity of the polymerase. e) The dideoxyribonucleotides would be used by the primase but not the DNA polymerase.

b) The dideoxyribounucleotides would be incorporated into newly synthesized DNA by DNA polymerase but would terminate further elongation of the DNA strand when so incorporated.

The signal for fusion of a synaptic vesicle with the plasma membrane is typically a) The movement of Ca++ through voltage-gated Ca++ channels, triggered by membrane depolarization (positive membrane potential) of the postsynaptic neuron. b) The movement of Ca++ through voltage-gated Ca++ channels, triggered by membrane depolarization (positive membrane potential) of the presynaptic neuron. c) The movement of Ca++ through voltage-gated Ca++ channels, triggered by membrane repolarization (negative membrane potential) of the postsynaptic neuron. d) The movement of Ca++ through voltage-gated Ca++ channels, triggered by membrane repolarization (negative membrane potential) of the presynaptic neuron. e) Binding of the acetylcholine neurotransmitter to the acetylcholine receptor.

b) The movement of Ca++ through voltage-gated Ca++ channels, triggered by membrane depolarization (positive membrane potential) of the presynaptic neuron.

The contractile ring that accomplishes cytokinesis consists of a) kinesins. b) actin microfilaments. c) interpolar microtubules. d) astral microtubules. e) the midbody.

b) actin microfilaments.

The protein that holds replicated chromosomes together during mitosis is a) condensin b) cohesin c) securin d) separase e) the anaphase promoting complex

b) cohesin

After dissociation of the LDL particle and the LDL receptor in the endosome, the LDL particle is _(1) and the LDL receptor is typically ___ (2) a) returned to the plasma membrane (1), degraded in the lysosome (2) b) degraded in the lysosome (1), returned to the plasmas membrane (2) c) degraded in the lysosome (1), degraded in the lysosome (2) d) returned to the plasma membrane (1), returned to the plasma membrane (2)

b) degraded in the lysosome (1), returned to the plasmas membrane (2)

During mitosis, (1) motors pull the astral microtubules towards the poles and (_2) motors pull the chromosomes toward the poles a) dynein (1), kinesin (2) b) dynein (1), dynein (2) c) kinesin (1), kinesin (2) d) kinesin (1), dynein (2) e) kinesin (1), myosin (2)

b) dynein (1), dynein (2)

The LDL receptor becomes dissociated from the LDL particle in the _________(1), and the LDL particle is typically_______(2). a) lysosome (1), degraded in the lysosome, with release of cholesterol to the cytosol (2) b) endosome (1), degraded in the lysosome, with release of cholesterol to the cytosol (2) c) endosome (1), returned to the plasma membrane(2) d) endosome (1), moved to the Golgi apparatus (2) e) multivesicular body (1), returned to the plasma membrane (2)

b) endosome (1), degraded in the lysosome, with release of cholesterol to the cytosol (2)

_________(1) interact with interpolar microtubules to push the two poles of the cells apart, and _____(2) interact with astral microtubules to pull the two poles towards the membranes of the cell during mitosis. a) dyneins (1), kinesins (2) b) kinesins (1), dyneins (2) c) dyneins (1), dyneins (2) d) kinesins (1), kinesins (2) e) kinesins (1), actins (2)

b) kinesins (1), dyneins (2)

The signal that directs proton pumps to the endosome is a) KDEL b) mannose 6 phosphate c) ubiquitin d) no signal (just bulk transport) e) aggregation with other pumps

b) mannose 6 phosphate

Which of the following conditions would provide the most favorable conditions for the synthesis of ATP by ATP synthase in mitochondria? a) proton gradient (with a higher proton concentration in the intermembrane space than in the mitochondrial matrix) and high ATP/low ADP in the matrix. b) proton gradient (with a higher proton concentration in the intermembrane space than in the mitochondrial matrix) and low ATP/high ADP in the matrix. c) proton gradient (with a higher proton concentration in the matrix than in the intermembrane space) and high ATP/low ADP in the matrix. d) proton gradient (with a higher proton concentration in the matrix than in the intermembrane space) and low ATP/highADP in the matrix. e) proton gradient (with a higher proton concentration in the mitochondrial intermembrane space than in the cytosol) and ADP in the cytosol but not in the mitochondrial matrix.

b) proton gradient (with a higher proton concentration in the intermembrane space than in the mitochondrial matrix) and low ATP/high ADP in the matrix.

Approximately 200 adenosines are added a) to the 5' end of most mRNAs b) the 3' end of most mRNAs c) in the middles of most mRNAs, with translated nucleotides downstream from them

b) the 3' end of most mRNAs

The proofreading function of DNA polymerase removes an incorrectly added deoxyribonucleotide from a) the 5' end of the newly synthesized strand b) the 3' end of the newly synthesized strand c) the 5' end of the template strand d) the 3' end of the template strand e) the 3' end of both the newly synthesized and template strand

b) the 3' end of the newly synthesized strand

The Anaphase-promoting complex _______(1) securin, thereby causing it to __________(2) so that separase is activated to _____(3). a) ubiquitinates (1), accumulate (2), cleave cohesins (3) b) ubiquitinates (1), degrade (2), cleave cohesins (3) c) ubiquitinates (1), degrade (2), insert cohesins around the chromatids (3) d) phosphorylates (1), accumulate (2), cleave cohesins (3) e) phosphorylates (1), degrade (2), insert cohesins around the chromatids (3)

b) ubiquitinates (1), degrade (2), cleave cohesins (3)

Which of the following is found for prokaryotic mRNAs but not for eukaryotic mRNAs? a) capping b) splicing c) production of more than one protein from a single mRNA d) A and B are both found in prokaryotes e) A, B and C are all found in prokaryotes

c) production of more than one protein from a single mRNA

The iron which holds onto electrons least tightly (lowest redox potential) during transport of electrons in the mitochondria is part of a) NADH b) cytochrome c) An Fe-sulfur protein d) hemoglobin e) the ATP synthase

c) An Fe-sulfur protein

N-oligosaccharyl transferase (OT) a) Adds sugars to dolichol phosphate. b) Adds branched chains of sugars to an unbranched chain in the ER lumen. c) Attaches a branched chain of sugars to certain Asn residues in proteins in the ER. d) Cuts transmembrane polypeptides at a target sequence and attaches the C-terminus of the resulting polypeptide to the GPI anchor. e) Removes sugars from already glycosylated proteins in the Golgi apparatus.

c) Attaches a branched chain of sugars to certain Asn residues in proteins in the ER.

Why does every DNA replication fork generate leading and lagging replication strands? a) Because helicase unwinds DNA in the 5' to 3' direction. b) Because DNA replication requires a double-stranded template to begin DNA synthesis. c) Because DNA is an antiparallel double helix. d) Because DNA polymerase can synthesize DNA in both the 5' to 3' and 3' to 5' direction. e) Because Okazaki fragments form on only one side of the replication bubble

c) Because DNA is an antiparallel double helix.

Which of the following would lead to the most depolarization of a neuronal membrane? a) Binding of high levels of GABA to a GABA receptor b) Binding of low levels of GABA to a GABA receptor c) Binding of high levels of acetylcholine to the nicotinic acetylcholine receptor d) Binding of low levels of acetylcholine to the acetylcholine receptor e) Binding of high levels of acetylcholine to the acetylcholine receptor and high levels of GABA to the GABA receptor

c) Binding of high levels of acetylcholine to the nicotinic acetylcholine receptor

The iron which holds onto electrons most tightly (highest redox potential) during transport of electrons in the mitochondria is part of a) Ubiquinone. b) Iron-sulfurcenters. c) Cytochromes. d) The ATP synthase. e) Hemoglobin.

c) Cytochromes.

The enzyme that seals the nicks left after synthesis of of DNA to fill the gaps between Okazaki fragments is a) primase. b) repair DNA polymerase. c) DNA ligase. d) telomerase. e) nuclease.

c) DNA ligase.

During translation, the small ribosomal subunit moves forward, thereby moving the peptide to the P site, when a) GTP is cleaved by EF-Tu. b) the peptide bond is synthesized by peptidyl transferase. c) EF-G-GTP cleaves GTP to produce GDP. d) the large ribosomal subunit also moves forward. e) the tRNA is released from the E site.

c) EF-G-GTP cleaves GTP to produce GDP.

Which of these most likely evolved last (i.e., in the most recent past)? a) electron transport pumps that pumped protons without ATP hydrolysis b) ATP-driven proton pumps c) Electron transport chains that used oxygen as the terminal electron acceptor d) Photosynthetic electron transport chains that split water molecules e) All of the above (A, B, C and D) had to evolve at the same time.

c) Electron transport chains that used oxygen as the terminal electron acceptor

Predict the membrane orientation in the endoplasmic reticulum (ER) of a protein that is synthesized with an N terminal cleaved ER signal sequence, followed by a stop-transfer sequence and then a start transfer sequence in more C terminal regions of the protein (with no more stop transfer sequences). Going from the N terminus to the C terminus, the orientation would be: a) N terminal end in the lumen, transmembrane segment, C terminal end in the cytosol. b) N terminal end in the cytosol, transmembrane segment, loop in the lumen, transmembrane segment, C terminal end in the cytosol. c) N terminal end in the lumen, transmembrane segment, loop in the cytosol, transmembrane segment, C terminal end in the lumen. d) N terminal end in the cytosol, transmembrane segment, C terminal end in the lumen. e) N terminal end in the cytosol, transmembrane segment, loop in the lumen, transmembrane segment, loop in the cytosol, transmembrane segment, C terminal end in the lumen.

c) N terminal end in the lumen, transmembrane segment, loop in the cytosol, transmembrane segment, C terminal end in the lumen.

Which of the following electron carriers has the lowest redox potential (most tendency to give up electrons)? a) ubiquinone b) iron sulfur centers c) NADH d) cytochromes e) oxygen

c) NADH

Protons are pumped by _(1) to accumulate high levels of protons in the _(2) for generation of ATP, while NADPH is generated by movement of electrons through (3) a) Photosystem I (1), thylakoids (2), Photosystem II (3) b) Photosystem I (1), stroma (2), Photosystem II (3) c) Photosystem II(1), thylakoids (2), Photosystem I (3) d) Photosystem II (1), stroma (2), Photosystem I (3) e) Photosystem II (1), stroma (2), Photosystem II (3)

c) Photosystem II(1), thylakoids (2), Photosystem I (3)

The electrons that are re-energized by photosystem I and eventually donated to NADPH come most directly from a) Water. b) P680. c) The cytochrome b6/f complex. d) Oxygen. e) Carbon dioxide.

c) The cytochrome b6/f complex.

DNA can be replicated in a test tube containing a mixture that includes DNA template strands and deoxyribonucleotides, Modified versions of deoxyribonucleotides can be added that lack a hydroxyl group at the 3' carbon and instead contain two hydrogen atoms at this carbon. What would be the effect of these "dideoxyribonucleotides" on DNA synthesis? a) The dideoxyribonucleotides would not be incorporated into DNA by any of the DNA replication enzymes. b) The dideoxyribonucleotides would be used by the primase but not the DNA polymerase. c) The dideoxyribounucleotides would be incorporated into newly synthesized DNA by DNA polymerase but would terminate further elongation of the DNA strand when so incorporated. d) The dideoxyribounucleotides would be incorporated into the DNA by DNA polymerase and serve as sites for elongation of the synthesized strand (just like normal deoxyribonucleotides). e) The dideoxyribonucleotides could be incorporated into the DNA by DNA polymerase but could not be excised by the 3' to 5' exonuclease activity of the polymerase.

c) The dideoxyribounucleotides would be incorporated into newly synthesized DNA by DNA polymerase but would terminate further elongation of the DNA strand when so incorporated.

You have generated two sets of vesicles, both with bacteriorhodopsin (which pumps protons out of bacteria in response to light) and the mitochondrial F1 ATPase inserted into the membranes of the vesicles. In both cases, the parts of the proteins that normally face the outside of the cell or the mitochondrial intermembrane space are inside the vesicles, and protons, ADP and inorganic phosphate are outside the vesicles. Both sets of vesicles are incubated with light, but one set also has an uncoupling agent present. What will each of the two vesicle sets do? a) Both will pump protons and generate ATP. b) Neither will pump protons and generate ATP. c) The set without the uncoupling agent will pump protons and generate ATP, while the set with the uncoupling agent will pump protons but will not generate ATP. d) The set with the uncoupling agent will pump protons and generate ATP, while the set without the uncoupling agent will pump protons but will not generate ATP. e) The set without the uncoupling agent will pump protons and generate ATP, while the set with the uncoupling agent will generate ATP but will not pump protons.

c) The set without the uncoupling agent will pump protons and generate ATP, while the set with the uncoupling agent will pump protons but will not generate ATP.

The skin of people with mutations that cause xeroderma pigmentosum is highly sensitive to UV light because a) the UV light produces more thymine dimers in their skin than in unaffected people b) UV light produces more mismatched DNA in their skin than in unaffected people. c) UV light produces the same amount of thymine dimers in their skin as for unaffected people but repair or removal of these thymine dimers is defective. d) A and B are both true e) A and C are both true

c) UV light produces the same amount of thymine dimers in their skin as for unaffected people but repair or removal of these thymine dimers is defective.

Which of the following DNA repairs typically involves removing a deoxyribonucleotide from just the most recently synthesized strand? a) a depurinated deoxyribonucleotide b) a deaminated deoxyribounucleotide c) a mismatched normal deoxyribonucleotide d) A and B are both correct answers. e) B and C are both correct answers.

c) a mismatched normal deoxyribonucleotide

What does telomerase use as a template for the synthesis of DNA? a) the DNA template of the lagging strand b) the DNA lagging strand c) an RNA molecule the encodes one strand of the telomere repeat d) the DNA template of the leading strand e) the DNA leading strand

c) an RNA molecule the encodes one strand of the telomere repeat

Which of the following is NOT required for initiation of transcription by RNA polymerase II in eukaryotes? a) TFIID b) A promoter-binding protein c) an RNA primer synthesized by another enzyme d) A helicase protein that unwinds DNA e) a kinase protein that phosphorylates RNA Pol II

c) an RNA primer synthesized by another enzyme

The phase of the mitotic cell cycle when each replicated chromosome is attached to a microtubule from each pole and aligns at the middle of the cell with other replicated chromosomes is a) interphase. b) prophase. c) metaphase. d) anaphase. e) telophase.

c) metaphase.

Which of the following conditions would provide the most favorable conditions for the transport of protons from the mitochondrial matrix to the intermembrane space, in the absence of electron transport? a) proton gradient (with a higher proton concentration in the intermembrane space than in the mitochondrial matrix) and high ATP/low ADP in the matrix. b) proton gradient (with a higher proton concentration in the intermembrane space than in the mitochondrial matrix) and low ATP/high ADP in the matrix. c) proton gradient (with a higher proton concentration in the matrix than in the intermembrane space) and high ATP/low ADP in the matrix. d) proton gradient (with a higher proton concentration in the matrix than in the intermembrane space) and low ATP/high ADP in the matrix. e) proton gradient (with a higher proton concentration in the mitochondrial intermembrane space than in the cytosol) and ADP in the cytosol but not in the mitochondrial matrix.

c) proton gradient (with a higher proton concentration in the matrix than in the intermembrane space) and high ATP/low ADP in the matrix.

DNA polymerases add new nucleotides to the _ (1) end of a growing strand while hydrolyzing a phosphoanhydride bond on the_(2) end of the added nucleotide to remove an incorrectly added nucleotide. a) 5' (1), 5' (2) b) 5' (1), 3' (2) c) 3' (1), 3' (2) d) 3' (1), 5' (2)

d) 3' (1), 5' (2)

Which of the following DNA repairs can involve removing a deoxyribonucleotide from either the most recently synthesized strand or the template strand of the DNA double helix? a) a depurinated deoxyribonucleotide b) a deaminated deoxyribounucleotide c) a mismatched normal deoxyribonucleotide d) A and B are both correct answers e) B and C are both correct answers.

d) A and B are both correct answers

Retention of a protein within a particular cisterna of the Golgi apparatus is thought to involve a) proteins that recognize each other via their membrane-spanning domains, preventing forward movement due to aggregation. b) proteins that move through the Golgi apparatus until the length of their membrane-spanning region matches the thickness of the bilayer. c) Receptors in different cisternae that recognize and bind to a targeting sequence in proteins that localize to a particular cisterna. d) A and B are both correct answers. e) A, B and C are all correct answers.

d) A and B are both correct answers.

A difference between transport of proteins into mitochondria and transport of proteins into the ER is a) transport of proteins into mitochondria occurs post-translationally, while it occurs cotranslationally into the ER. b) transport of proteins into mitochondria must occur across two lipid bilayers, while it occurs across one lipid bilayer into the ER. c) transport of proteins into mitochondria occurs while the proteins are in a fully folded state, while the proteins are unfolded during transport into the ER. d) A and B are both correct. e) A, B and C are all correct.

d) A and B are both correct.

Which of the following neurotransmitter-gated channels is (are) excitatory and therefore tend(s) to produce depolarization of neurons (thereby making the membrane potential more positive)? a) the nicotinic acetylcholine receptor b) the glutamate receptor c) the GABA receptor d) A and B are both excitatory but not C. e) A, B and C are all excitatory.

d) A and B are both excitatory but not C.

Which of the following carry electrons in the energized state? a) ATP b) NADH c) NADP+ d) A and B are carrier molecules in the energized state. e) A, B and C are carrier molecules in the energized state.

d) A and B are carrier molecules in the energized state.

Which of the following mRNA-related events is (are) found in eukaryotes but NOT in prokaryotes? a) Splicing b) Capping c) Production of single mRNAs that encode multiple proteins d) A and B are found in eukaryotes but not in prokaryotes. e) A, B and C are found in eukaryotes but not in prokaryotes.

d) A and B are found in eukaryotes but not in prokaryotes.

Which of the following enzymes require(s) a primer with a 3' end to synthesize nucleic acid? a) DNA polymerase at the replication fork b) telomerase c) primase d) A and B both require a primer. e) A, B and C all require a primer.

d) A and B both require a primer.

Which of the following assays could be used to support the conclusion that a protein mixed with membranes in vitro has moved into a membrane-bound compartment? a) After mixing the protein and the membranes, the protein becomes resistant to protease degradation but becomes sensitive to protease after the mixture is treated with detergent. b) After mixing the protein and the membranes, the protein becomes resistant to protease degradation if the mixture is treated with a detergent but is sensitive to protease if the mixture is not mixed with detergent. c) After mixing the protein and membranes, the protein is found in a higher molecular weight fraction after centrifugation than it is found without mixing. d) A and C would both support the conclusion. e) B and C would both support the conclusion.

d) A and C would both support the conclusion.

Which of the following would NOT be a way that a cell could store potential energy to use later? a) generation of ATP from ADP and Pi b) generation of NADPH form NADP+ and electrons/protons c) generation of NADH form NAD+ and electrons/protons d) Accumulation of carbon dioxide on one side of a membrane e) Accumulation of Na+ on one side of a membrane

d) Accumulation of carbon dioxide on one side of a membrane

You have a temperature-sensitive dynamin mutant, for which elevated temperatures cause the dynamin to be nonfunctional. The mutant phenotype at elevated temperature would be: a) Clathrin does not coat the outside of vesicles, which are nevertheless released. b) Cargo receptors do not move into clathrin coated membrane patches. c) Vesicles form without clathrin coats and are not released from membranes. d) Clathrin-coated vesicles form but are not released from membranes. e) Clathrin-coated vesicles form, are released and function normally.

d) Clathrin-coated vesicles form but are not released from membranes.

Channelrhodopsin is opened by ____(1) and activates neurons by allowing ____(2) ions to pass into the cell. a) Membrane depolarization (1), Ca++ (2) b) Membrane depolarization (1), Na+ (2) c) Light (1), Cl- (2) d) Light (1), Na+ (2) e) Ca++ ions (1), Na+ (2)

d) Light (1), Na+ (2)

Predict the membrane orientation in the endoplasmic reticulum (ER) of a protein that is synthesized with an N terminal anchor sequence that is not cleaved during insertion and does not translocate into the lumen, followed by a stop-transfer sequence and then a start-transfer sequence in more C terminal regions of the protein (with no more signal or anchor sequences). Going from the N terminus to the C terminus, the orientation would be: a) N terminal end in the cytosol, transmembrane segment, C terminal end in the lumen. b) N terminal end in the cytosol, transmembrane segment, loop in the lumen, transmembrane segment, C terminal end in the cytosol. c) N terminal end in the lumen, transmembrane segment, loop in the cytosol, transmembrane segment, C terminal end in the lumen. d) N terminal end in the cytosol, transmembrane segment, loop in the lumen, transmembrane segment, loop in the cytosol, transmembrane segment, C terminal end in the lumen. e) N terminal end in the lumen, transmembrane segment, C terminal end in the cytosol.

d) N terminal end in the cytosol, transmembrane segment, loop in the lumen, transmembrane segment, loop in the cytosol, transmembrane segment, C terminal end in the lumen.

The K+ leak channel a) Allows K+ ions and any positive ions smaller than K+ to leak across the membrane. b) Is opened only at positive membrane potentials. c) Is always open. d) Produces a negative membrane potential by allowing a small number of K+ ions to move from the cytosol to the extracellular side of the cell. e) All of the above are true.

d) Produces a negative membrane potential by allowing a small number of K+ ions to move from the cytosol to the extracellular side of the cell.

You have a single voltage-gated Na+ channel in a patch-clamped piece of membrane that has been removed from the surface of the cell. Higher levels of Na+ are present inside the electrode. How would the current measured by the patch clamp electrode with a positive membrane potential compare with the current measured with a negative membrane potential? a) In both cases there would be no current measured. b) In both cases the current would be measured continuously. c) With the positive membrane potential, the current would be measured continuously because the membrane potential would open the channel, while with the negative membrane potential there would no current measured. d) With the positive membrane potential, there would be high frequency of current pulses because the membrane potential would tend to open the channel, while with the negative membrane potential there would a low frequency of pulses. e) With the negative membrane potential, there would be high frequency of current pulses because the membrane potential would tend to open the channel, while with the positive membrane potential there would a low frequency of pulses.

d) With the positive membrane potential, there would be high frequency of current pulses because the membrane potential would tend to open the channel, while with the negative membrane potential there would a low frequency of pulses.

The lysosome degrades which of the following? a) an extracellular ligand taken up by endocytosis b) a bacterium taken up by phagocytosis c) a damaged mitochondrion taken up by autophagocytosis. d) A and B are both correct e) A, B and C are all correct.

e) A, B and C are all correct.

Transcription takes place in DNA bubbles that differ from DNA replication bubbles because a) transcription bubbles do not expand in both directions. b) transcription bubbles do not transcribe all of the genomic DNA. c) transcription bubbles do not use both strands as template. d) transcription bubbles produce a single-stranded product (RNA, not DNA). e) All of the above are correct.

e) All of the above are correct.

Transcription takes place in single-stranded DNA bubbles that differ from DNA replication bubbles because a) transcription bubbles do not expand in both directions. b) transcription bubbles do not transcribe all of the genomic DNA. c) transcription bubbles do not use both strands as template. d) transcription bubbles produce a single-stranded product (RNA, not DNA). e) All of the above are correct.

e) All of the above are correct.

Which of the following is a destination of a transport vesicle produced in the Golgi apparatus? a) The endoplasmic reticulum b) another cisterna of the Golgi apparatus c) the plasma membrane d) the endosome e) All of the above are destinations of transport vesicles produced in the Golgi apparatus

e) All of the above are destinations of transport vesicles produced in the Golgi apparatus

In the dark reactions of photosynthesis, which of the following is NOT a reactant? a) Carbon dioxide b) ATP c) NADPH d) Ribulose bisphosphate e) All of the above are reactants.

e) All of the above are reactants.

Proteins inserted completely into the lumen of the endoplasmic reticulum a) are folded by BiP. b) are transported through channels into the cytosol and degraded if they misfold. c) trigger the unfolded protein response if they misfold, leading to upregulation of ER proteins to counteract the misfolded proteins. d) will not become membrane proteins in any part of the endomembrane system or plasma membrane. e) All of the above are true.

e) All of the above are true.

Which of the following mechanisms can be used to pump protons across the inner membranes of mitochondria? a) Pumps switch to a high energy state when they bind a proton in the matrix, lose energy in response to the transport of electrons, and then change to a low affinity state for the proton in the intermembrane space. b) Pumps switch to a low energy state when they bind a proton in the matrix, gain energy in response to the transport of electrons, and then change to a low affinity state for the proton in the intermembrane space. c) Placement of an electron acceptor on the inside of the inner mitochondrial membrane and an electron donor on the outside can move a co-transported proton to the outside. d) A and C are both possible mechanisms e) B and C are both possible mechanisms

e) B and C are both possible mechanisms

Which of the following mechanisms can be used to pump protons across the inner membranes of mitochondria? a) Pumps switch to a high energy state when they bind a proton in the matrix, lose energy in response to the transport of electrons, and then change to a low affinity state for the proton in the intermembrane space. b) Pumps switch to a low energy state when they bind a proton in the matrix, gain energy in response to the transport of electrons, and then change to a low affinity state for the proton in the intermembrane space. c) Placement of an electron acceptor on the inside of the inner mitochondrial membrane and an electron donor on the outside can move a co-transported proton to the outside. d) A and C are both possible mechanisms. e) B and C are both possible mechanisms.

e) B and C are both possible mechanisms.

Which of the following does (do) the increasingly acid pH of the endosomal to lysosomal pathway produce? a) Activates the enzyme which adds mannose-6-phosphate to proteins. b) Separates soluble cargo proteins from their membrane receptors. c) Activates hydrolases that break down a variety of biological molecules. d) Activates proton pumps in the membranes of lysosomes. e) B, C and D are produced by increasingly acid pH.

e) B, C and D are produced by increasingly acid pH.

Which of the following would be found on a vesicle that has just started to interact with its acceptor compartment? a) a coat protein b) a cargo receptor for a protein that is soluble in the vesicle c) a Rab protein d) a V-SNARE protein e) B, C and D would be found on this vesicle

e) B, C and D would be found on this vesicle

The drug dintrophenol (DNP) renders the inner mitochondrial membrane permeable to protons, while the drug nigericin renders this membrane permeable to K+. How will the electrochemical gradient across the inner membrane change in response to these drugs? a) Neither drug will affect the electrochemical gradient. b) DNP and nigericin will both eliminate the electrochemical gradient entirely. c) DNP will eliminate the electrical and chemical parts of the gradient, while nigericin will increase the gradient by enhancing the electrical part of the gradient. d) Nigericin will eliminate both the electrical and chemical gradients, while DNP will only affect the proton concentration part of the gradient. e) DNP will eliminate both the electrical and chemical gradients, while nigericin will only affect the electrical part of the gradient.

e) DNP will eliminate both the electrical and chemical gradients, while nigericin will only affect the electrical part of the gradient.

Using genetic engineering techniques, you attach an N-terminal cleaved ER signal sequence to a protein that also has a nuclear localization signal in the middle. What will happen to the protein? a) It will be torn in half, with the N-terminal half going to the ER and the C-terminal half to the nucleus. b) It will remain in the cytosol. c) It will be translocated to the nucleus. d) Some of the full length protein will go to the nucleus and some to the ER. e) It will be translocated to the ER.

e) It will be translocated to the ER.

Using genetic engineering techniques, you attach an N-terminal cleaved ER signal sequence to a protein that also has a nuclear localization signal in the middle. What will happen to the protein? a) It will be torn in half, with the N-terminal half going to the ER and the C-terminal half to the nucleus. b) It will remain in the cytosol. c) It will be translocated to the nucleus. d) Some of the full length protein will go to the nucleus and some to the ER. e) It will be translocated to the ER.

e) It will be translocated to the ER.

You have constructed phospholipid vesicles that contain Na+/K+ pumps as the sole membrane protein. The portion of the pump that normally faces the cytosol is oriented towards the outside of the vesicles. The solutions inside the vesicles and outside the vesicles have both Na+ ions and K+ ions, but ATP is not present on either side. What would happen? a) Very little Na+ would move inside the vesicle (only one partial cycle of all the pumps would occur, moving a single cycle of Na+ to the inside of the vesicle) b) Very little Na+ would move outside the vesicle (only one partial cycle of all the pumps would occur, moving a single cycle of Na+ to the outside of the vesicle). c) Na+ and K+ would be pumped repeatedly out of the vesicle. d) Na+ and K+ would be pumped repeatedly into the vesicle. e) No Na+ or K+ would move.

e) No Na+ or K+ would move.

The opening or which of the following channels tends to induce opening of more channels of the same type? a) The acetylcholine receptor b) The voltage-gated K+ channel c) The K+ leak channel d) The glycine receptor e) The voltage-gated Na+ channel

e) The voltage-gated Na+ channel

The opening or which of the following channels tends to induce opening of more channels of the same type? a) The acetylcholine receptor b) The voltage-gated K+ channel c) The K+ leak channel d) The glycine receptor e) The voltage-gated Na+ channel

e) The voltage-gated Na+ channel

What would happen if the membrane of a cell at resting membrane potential suddenly became highly permeable to Na+ ions? a) Net Na+ flow would be from the inside of the cell to the outside of the cell. b) Net Na+ flow would be from the outside of the cell to the inside of the cell. c) The membrane potential would change from negative to positive. d) The membrane potential would change from positive to negative e) A and C would both happen. f) B and C would both happen.

f) B and C would both happen.