Bio 105 Chapter 16
11. Which of the following is least likely to occur in a non-mutant bacterial cell? a. -galactoside transacetylase is present at a high concentration when -galactoside is present at a low concentration. b. -galactoside transacetylase is produced at very low levels in the absence of lactose. c. -galactoside transacetylase is produced at very low levels when glucose is abundant. d. -galactoside transacetylase is produced at high levels when lactose is at a high concentration and glucose is not available. e. -galactoside transacetylase and β-galactoside are both present in very low concentrations.
a
16. The trp operon a. codes for proteins needed for tryptophan synthesis. b. codes for proteins needed to metabolize tryptophan. c. is activated by the presence of tryptophan. d. is inducible by tryptophan. e. is inducible by lactose (or allolactose).
a
17. Inducible and repressible systems are similar in that a. in both systems the regulatory molecules function by binding to the operator. b. both systems usually control biosynthetic pathways. c. both systems usually control catabolic pathways. d. both systems block transcription through the presence of a regulatory protein. e. both systems are unique to prokaryotes.
a
26. How does gene regulation differ between prokaryotes and multicellular eukaryotes? a. Different cells in eukaryotes vary in the types and number of genes they express. b. Protein-DNA interactions only occur in eukaryotes. c. Protein-DNA interactions only occur in prokaryotes. d. Both a and c e. Both b and c
a
28. The TATA box is a(n) a. sequence close to the promoter region of many genes. b. square-shaped sequence. c. enhancer consensus sequence. d. activator sequence necessary for proper translation. e. transcription factor.
a
34. If a mutation in a silencer makes it much more difficult for it to be bound by proteins, which of the following is most likely to occur? a. A specific gene near the silencer will be transcribed all the time, even when not needed. b. There will be a large decrease in transcription rates for most genes. c. There will be a large increase in transcription rates for most genes. d. The rate of transcription of a specific gene located near the silencer will be reduced, even when it is needed the most. e. Transcription will be terminated prematurely.
a
43. The term "lysogeny" refers to a. the stable integration of bacteriophage DNA into the bacterial chromosome. b. the excision of bacteriophage DNA from the bacterial chromosome. c. the lysing of a bacterium by a bacteriophage. d. mutation induced by a bacteriophage. e. the reciprocal exchange of genetic material between a bacteriophage and a bacterium.
a
47. What is the difference between a prophage and a provirus is that, based on what you know about HIV and bacteriophage ? a. The host of a prophage is a bacterium, whereas the host of a provirus is a eukaryote. b. A provirus is in lysogeny, whereas a prophage is the provirus after a return to the lytic phase. c. A prophage is in lysogeny, whereas a provirus is the prophage after a return to the lytic phase. d. The host of a prophage is a eukaryote, whereas the host of a provirus is a bacterium. e. A prophage is regulated by cI, whereas a provirus is regulated by Cro.
a
50. Which of the following AIDS treatments works by preventing the formation of provirus? a. Integrase inhibitors b. Protease inhibitors c. reverse transcriptase inhibitors d. Tat e. Cro
a
61. Genomic imprinting a. marks the parental origin of alleles. b. explains why euchromatin and heterochromatin are different. c. explains differences in the epigenomes of adult monozgotic twins. d. alters the DNA sequence. e. is not found in mammals.
a
65. The Barr body indicates a. X chromosome inactivation. b. cell death. c. genomic imprinting. d. posttranslational control of eukaryotic gene expression. e. stress response.
a
67. One of the genes that is known to be transcribed from the inactive X chromosome is a. Xist. b. ZIST. c. inactivation controller protein. d. DNA methyltransferase. e. methyl-X.
a
70. Alternative splicing in humans is _______ pronounced than it is in chimpanzees, allowing for _______ different proteins per gene in humans than in chimpanzees. a. more; more b. more; fewer c. just as; more d. less; more e. less; fewer
a
10. In comparison with genes in bacterial operons, genes that encode for stress responses in plants a. are located closer together on the chromosome. b. are located farther apart on the chromosome. c. are not coordinately regulated. d. do not alter their expression levels due to transcription factor binding. e. do not respond to changes in environmental conditions.
b
22. Bacterial promoters of different housekeeping genes a. are nearly identical throughout their sequence. b. can vary in sequence but share consensus sequences at which they are very similar. c. can vary in sequence but share sigma factors at which they are very similar. d. can vary in sequence but share regulatory sequences at which they are very similar. e. can vary in sequence, and share no common motifs.
b
32. A DNA sequence is several thousands of nucleotides distant from the promoter. When this sequence is bound by a protein, transcription rates increase greatly. This sequence is most likely a(n) a. TATA box. b. enhancer. c. operon. d. promoter. e. consensus sequence.
b
33. When an enhancer is bound, it a. increases the stability of a specific mRNA. b. stimulates transcription of a specific gene. c. stimulates transcription of nearly all genes. d. stimulates splicing of a specific mRNA. e. stimulates splicing of nearly all mRNAs.
b
36. Helix-turn-helix is a _______ found in a _______. a. structural motif; promoter b. structural motif; transcription factor c. consensus sequence; promoter d. consensus sequence; enhancer e. consensus sequence; transcription factor
b
41. If a loss-of-function mutation occurs in one of the early genes in a lytic bacteriophage, which of the following changes is most likely to occur? a. Late genes will be turned on. b. The host genes will remain turned on. c. The viral genome will be replicated. d. New viral capsid proteins will be produced. e. Proteins that lyse the host cell will be produced.
b
49. Gene regulation by tat in HIV occurs at the level of a. transcription initiation. b. transcription elongation. c. mRNA stability. d. translation initiation. e. translation elongation.
b
53. If a mutation causes a reduction in the production of demethylase, the expected effect will be _______ in the amount of overall methylation and therefore _______ in overall gene expression. a. an increase; an increase b. an increase; a decrease c. no change; an increase d. decrease; an increase e. decrease; a decrease
b
57. If a mutation causes a decrease in the activity of histone acetyltransferases, histones will most likely have a _______ affinity for DNA, and there would be _______ in transcription rates. a. greater; an increase b. greater; a decrease c. reduced; an increase d. reduced; no change e. reduced; a decrease
b
58. The activity of _______ tends to lead to increased transcription. a. histone deacetylase b. histone acetyltransferase c. DNA methyltransferase d. maintenance methylase e. RNA polymerase
b
59. Identical twins show a. similar methylation patterns throughout their lives. b. similar methylation patterns as children, but divergent patterns as adults. c. divergent methylation patterns as children, but similar patterns as adults. d. divergent methylation patterns as children, similar patterns as teenagers, and divergent patterns as adults. e. divergent methylation patterns throughout their lives.
b
6. An inducer a. inhibits the synthesis of the needed enzyme(s). b. stimulates the synthesis of the needed enzyme(s). c. binds to the promoter and prevents the repressor from binding to the operator. d. binds to the operator and prevents the repressor from binding at this site. e. is the same as a promoter.
b
63. Which of the following statements about genomic imprinting is false? a. Prader-Willi syndrome is a consequence of a deletion in an imprinted gene. b. Most imprinted genes involve sexual differentiation during puberty. c. In imprinted genes, alleles derived from the father have a different methylation state than genes derived from the mother. d. Genomic imprinting is an epigenetic process. e. All of the above are true; none is false.
b
73. According to the following descriptions, which gene is most likely regulated at the posttranscriptional level? a. Gene A, which shows a strong positive correlation between the amount of mRNA produced and the amount of protein produced b. Gene B, which shows no clear correlation between the amount of mRNA produced and the amount of protein produced c. Gene C, which lies near the heterochromatin d. Gene D, which has more than a typical number of CpG islands e. Gene E, which has fewer than a typical number of CpG islands
b
74. Ubiquitin forms a complex with proteins and then binds with _______, forming a sort of "molecular chamber of doom" where proteins are digested into small peptides and amino acids. a. the extracellular space b. a proteasome c. mitochondria d. lysosomes e. the Golgi apparatus
b
9. -galactoside transacetylase is a. a promoter. b. encoded by a structural gene. c. a constitutive protein. d. usually produced at high levels when -galactoside is produced at low levels. e. usually produced at low levels when -galactoside is produced at high levels.
b
12. Place the following terms in order from left to right assuming transcription is also occurring in this direction. a. Operator, promoter, structural genes b. Operator, structural genes, promoter c. Promoter, operator, structural genes d. Promoter, structural genes, operator e. Structural genes, promoter, operator
c
18. A certain operon has structural genes that encode enzymes involved in the synthesis of a glycopeptide. This system is likely to be _______, and _______ will most likely bind to the operator. a. inducible; the glycopeptide b. inducible; one or more molecules used in the production of the glycopeptide c. repressible; the glycopeptide d. repressible; one or more molecules used in the production of the glycopeptide e. repressible; no molecules
c
21. Catabolite repression would least likely be found in a metabolic network a. involved in breaking down sugars. b. involved in breaking down lipids. c. involved in the production of glycoproteins. d. in Gram-positive bacteria. e. in Gram-negative bacteria.
c
27. The TATA box in eukaryotes is most similar to _______ in prokaryotes. a. sigma factors b. the entire promoter c. a consensus sequence in the promoter d. an operator e. an inducer
c
3. How do negative regulation and positive regulation in bacteria differ? a. Only negative regulation involves promoters. b. Only positive regulation involves promoters. c. In negative regulation, transcription is reduced when the promoter is bound. d. In positive regulation, transcription is reduced when the promoter is bound. e. Positive regulation must occur at an earlier stage than negative regulation.
c
30. What is the main difference between general and specific transcription factors? a. Specific transcription factors are found only in multicellular animals, whereas general transcription factors are found in most eukaryotes. b. Specific transcription factors are found only in multicellular plants, whereas general transcription factors are found in most eukaryotes. c. Specific transcription factors bind to regulatory sequences of fewer genes than general transcription factors do. d. Specific transcription factors bind regulatory sequences more tightly than general transcription factors do. e. Specific transcription factors bind regulatory sequences less tightly than general transcription factors do.
c
35. In a fly, the transcription rates of a gene that codes for an enzyme vary tremendously among different cell types. The most likely reason for these differences is that different cell types have different a. promoters. b. inducers. c. transcription factors present. d. silencers. e. enhancers.
c
39. Viruses are a. cells containing DNA and protein. b. larger than most bacteria. c. acellular. d. able to take in nutrients and expel wastes. e. mutated forms of DNA.
c
44. A mutation in the cro gene of a virus decreases its expression. This mutation would make entering lysogeny _______ likely. A mutation that decreases the expression of the cI gene would have _______ effect. a. more; a similar b. more; no c. more; the opposite d. less; a similar e. less; the opposite
c
48. If an HIV lineage obtains a mutation that causes its tat protein to be somewhat less able to bind to RNA, the most likely result would be a. more initiation of transcription. b. less initiation of transcription. c. the termination of more partial transcripts, and thus the making of fewer complete transcripts. d. the termination of fewer partial transcripts, and thus the making of more complete transcripts. e. a reduction in the stability of complete transcripts.
c
5. Which of the following is a carrier protein? a. Lactose b. β-galactoside c. β-galactoside permease d. β-galactoside transacetylase e. Glucose
c
60. Two identical twins show very similar methylation patterns when they are 4 years old, but these patterns diverged considerably by the time they are 40 years old. What is the most likely explanation for this? a. It is an effect of different genomic imprinting in the twins. b. It is due to different alternative splicing in the twins. c. It is due to the twins experiencing different environments as adults. d. It is due to different levels of histone acetyltransferase in the twins. e. It is due to differences the twins experienced in utero.
c
64. Heterochromatin stains _______ than euchromatin, and is _______ transcriptionally active. a. darker; more b. darker; just as c. darker; less d. lighter; more e. lighter; less
c
72. The product of lin-4 is a _______ that regulates lin-14, which is a _______. a. transcription factor; transcription factor b. transcription factor; microRNA c. microRNA; transcription factor d. microRNA; microRNA e. methylase; transcription factor
c
75. Some metabolic pathways are regulated in part by changes in the rate of degradation of key enzymes. This is an example of a. operon control. b. transcriptional control. c. posttranslational control. d. genomic imprinting. e. X inactivation.
c
8. In comparison with regulation of the production of enzymes, allosteric regulation of enzyme activity is _______ and _______ energetically efficient. a. faster; more b. faster; about as c. faster; less d. slower; more e. slower; less
c
1. In teenage children of women who suffered physical abuse while pregnant, the glucocorticoid receptor has a promoter region a. with more methylated bases than are typical. b. with fewer methylated bases than are typical. c. with epigenetic changes. d. Both a and c e. Both b and c
d
15. A certain enzyme is synthesized whenever the solution in which the cells are growing lacks substance X. This phenomenon is most likely an example of a(n) _______ system. a. inducible b. positive c. negative d. repressible e. positive-negative
d
2. The earlier the cell intervenes in the process of protein synthesis, the _______ energy it wastes. Thus, cells will tend to regulate protein synthesis _______. a. more; at the earliest possible stage b. more; at all stages c. more; at the latest possible stage d. less; at the earliest possible stage e. less; at the latest possible stage
d
29. In eukaryotes, the earliest stage of regulatory control that occurs largely outside of the nucleus is a. transcriptional control. b. chromatin remodeling. c. processing control. d. mRNA stability control. e. translational control.
d
31. Which of the following statements about TFIID is false? a. It is the first transcription factor to bind to the TATA box. b. Its shape changes after it binds to the TATA box. c. It attracts other transcription factors to the transcription initiation complex. d. It is a specific transcription factor. e. All of the above are true; none is false.
d
37. Marius Wernig and his team were able to convert skin fibroblasts into neurons by a. manipulating promoters. b. changing inducers. c. altering RNA polymerase. d. changing transcription factors. e. adjusting the temperature at critical developmental points.
d
40. In a bacteriophage undergoing a lytic phase, the early genes _______ the host genes and _______ the late genes. a. stimulate; stimulate b. stimulate; have no effect on c. stimulate; inhibit d. inhibit; stimulate e. inhibit; inhibit
d
42. Early genes of a lytic bacteriophage are transcribed by a. late genes. b. viral RNA polymerase from earlier lytic cycles. c. host DNA polymerase. d. host RNA polymerase. e. reverse transcriptase.
d
52. Which of the following enzymes allows methylation changes to be passed on after DNA replication? a. Demethylase b. DNA methyltransferase c. Methylheritablase d. Maintenance methylase e. CpG
d
54. Methylation most often occurs to _______ that are next to _______. a. adenines; cytosines b. adenines; guanines c. cytosines; adenines d. cytosines; guanines e. guanines; adenines
d
55. Nucleosomes disaggregate (or "open") to allow transcription and then reaggregate a. through alternative splicing. b. by methylation and demethylation. c. through alternation of nucleotides. d. by acetylation and deacetylation. e. through insertion of nucleotides.
d
62. Angelman syndrome results from a. excess histone acetyltransferase. b. a deficiency of histone acetyltransferase. c. the deletion of a transcriptionally active allele of an imprinted region. d. the deletion of a transcriptionally inactive allele of an imprinted region. e. failure to form a Barr body.
d
69. The expression of some genes can be regulated in part by the pattern of RNA splicing. This is an example of a. DNA methylation. b. transcriptional regulation. c. pretranscriptional control d. posttranscriptional control. e. genomic imprinting
d
7. Actin, which is part of many cellular structures and has several functions, is produced at constant levels in nearly all cells. It is best described as a(n) _______ protein. a. inducible b. repressible c. conditional d. constitutive e. regulated
d
71. Supplying nematodes with an excess of the product of lin-4 would most likely lead to a(n) _______ of lin-14 product, with the phenotypic consequences of _______. a. excess; repeating the pattern of development in the first larval stage b. excess; skipping the first larval stage and going straight to the second c. deficiency; repeating the pattern of development in the first larval stage d. deficiency; skipping the first larval stage and going straight to the second e. deficiency; turning hermaphrodites into males
d
13. In a bacterial cell, β-galactosidase is at high concentrations but -galactoside permease is at very low concentrations. Which of the following is the most likely explanation? a. Both glucose and lactose are at high concentrations. b. Both glucose and lactose are at low concentrations. c. The operator has a mutation. d. The promoter has a mutation. e. One of the structural genes has a mutation.
e
14. In a repressible operon, the repressor molecule a. is the substrate of the metabolic pathway. b. can repress the transcription of the operon on its own. c. is a molecule made from the operon. d. binds to the mRNA. e. must first be activated by a co-repressor.
e
19. To be activated, the CRP must first bind a. the repressor molecule. b. the repressor protein. c. the activator protein. d. the co-repressor molecule. e. cAMP.
e
20. In bacterial cells, the concentration of cAMP is _______ correlated with the concentration of glucose; hence, glucose concentrations should _______ correlated with the amount of transcription in the lac operon (assuming that lactose is abundant). a. positively; be positively b. positively; be inversely c. not; not be d. inversely; be positively e. inversely; be inversely
e
23. Sigma factors bind to a. promoters with no specificity. b. specific types of promoters. c. repressors. d. co-repressors. e. RNA polymerases.
e
24. How does regulation of stress response proteins in plants differ from regulation of enzymes produced from a bacterial operon? a. Expression of stress response proteins is coordinately regulated; expression of bacterial operon genes is not. b. Expression of bacterial operon genes is coordinately regulated; expression of stress response proteins is not. c. Regulation of stress response proteins involves DNA-protein interactions; regulation of bacterial operon genes does not. d. Regulation of bacterial operon genes involves DNA-protein interactions; regulation of stress response proteins does not. e. None of the above
e
25. Eukaryotic gene regulation differs from prokaryotic gene regulation in that a. there is no negative control in eukaryotes. b. there is no positive control in prokaryotes. c. there is no negative control in prokaryotes. d. transcription and translation occur at the same location in eukaryotes, but at different locations in prokaryotes. e. transcription and translation occur at the same location in prokaryotes, but at different locations in eukaryotes.
e
38. The stress response elements in plants are a. transcription factors. b. inducers. c. RNA sequences. d. enzymes. e. DNA sequences.
e
4. In E. coli metabolism, _______ is the preferred energy source because it is _______. a. lactose; more abundant b. lactose; easier to metabolize c. glucose; more abundant d. glucose; less abundant e. glucose; easier to metabolize
e
45. Cro protein _______ the expression of the cI gene. cI protein _______ the expression of the cro gene. a. stimulates; stimulates b. stimulates; has no effect on c. has no effect on; stimulates d. inhibits; stimulates e. inhibits; inhibits
e
46. If the environment experienced by bacteriophage λ deteriorates, the change will most likely _______ the lifespan of cI protein. This result will have the effect of _______. a. increase; maintaining lysogeny b. increase; increasing the production of LexA c. increase; making entry into the lytic phase more likely d. decrease; maintaining lysogeny e. decrease; making entry into the lytic phase more likely
e
51. Which of the following statements about epigenetics is false? a. One type of epigenetic change occurs via DNA methylation. b. One type of epigenetic change occurs via chromosomal protein alterations. c. Epigenetic changes can lead to gene expression changes. d. Epigenetic changes do not change the DNA sequence. e. All of the above are true; none is false.
e
56. The addition of acetyl groups makes histones _______ positively charged, and thus _______ their affinity for DNA. a. more; increases b. more; decreases c. less; increases d. less; has no effect on e. less; decreases
e
66. If each interphase nucleus in a preparation of normal rat epithelial cells is found to contain a single Barr body, one can conclude that a. the cells have an excess of DNA methyltransferase. b. the cells have a deficiency of DNA methyltransferase. c. all of the chromatin in these cells is inactive. d. the cells came from a male rat. e. the cells came from a female rat.
e
68. Posttranscriptional control in eukaryotes a. occurs mainly via methylation and demethylation. b. can only regulate the amount of product, not the type of product. c. takes place only in the nucleus. d. takes place only in the cytoplasm. e. can involve several different types of mechanisms.
e
