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Test File to accompany Life: The Science of Biology, Ninth Edition Sadava • Hillis • Heller • Berenbaum Chapter 16: Regulation of Gene Expression TEST FILE QUESTIONS (By Catherine Ueckert) Multiple Choice 1. CREB is a transcription factor that regulates gene expression. It binds to DNA and activates promoters of genes involved in addictive behaviors in alcoholism. Researchers compared CREB levels in the brains of a strain of rats called P rats and wild-type rats. When P rats consumed alcohol, a. the total levels of CREB increased. b. the total levels of CREB decreased. c. the total levels of CREB remained the same. d. levels of phosphorylated CREB increased. e. levels of phosphorylated CREB decreased. Answer: d Textbook Reference: 16.0 Alcoholism and the control of gene expression Page: 342–343 Bloom’s Category: 2. Understanding 2. Which of the following statements about viruses is true? a. They are not cells. b. They can regulate the movements of substances into and out of the cell. c. They can reproduce outside living cells. d. They are large and therefore easy to study. e. They are readily destroyed by antibiotics. Answer: a Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 343 Bloom’s Category: 1. Remembering 3. 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. Answer: c Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 343 Bloom’s Category: 1. Remembering 4. Viruses are composed of a. nucleic acids only. b. proteins only. c. nucleic acids and proteins. d. nucleic acids, proteins, and organelles. e. nucleic acids and proteins, although a few also have organelles. Answer: c Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 343 Bloom’s Category: 1. Remembering 5. Viruses a. arise from preexisting viruses. b. replicate their DNA before they reproduce. c. develop and reproduce only within the cells of hosts. d. cannot replicate. e. None of the above Answer: c Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 343 Bloom’s Category: 2. Understanding 6. Beginning with a single bacterium, how many cells would be present after 4 hours of growth if they can double every 20 minutes? a. 12 b. 24 c. 64 d. 4,096 e. 34,217,728 Answer: d Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 344–345 Bloom’s Category: 3. Applying 7. In transduction, a. only a particular part of the bacterial chromosome can be transferred. b. a part of the bacterial chromosome may be transferred. c. only the F plasmid can be transferred. d. only the part of the bacterial chromosome near the F plasmid can be transferred. e. None of the above Answer: b Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 345 Bloom’s Category: 2. Understanding 8. The transfer of genes by a bacteriophage vector characterizes which type of gene transfer in bacteria? a. Transformation b. Conjugation c. Transduction d. Transference e. None of the above Answer: c Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 345 Bloom’s Category: 2. Understanding 9. 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. exchange of genetic material between a bacteriophage and a bacterium. Answer: a Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 345 Bloom’s Category: 2. Understanding 10. Which of the following statements about the lytic cycle is true? a. The phage DNA integrates into the bacterial chromosome. b. Temperate viruses are formed. c. Prophages are replicated. d. The host cell lyses. e. Immunity to a specific strain of phage may result. Answer: d Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 345 Bloom’s Category: 4. Analyzing 11. Lysis of the host cell is caused by a. the cell’s bursting due to the large number of viral particles. b. the cell’s opening up in an attempt to release the viruses. c. an attack on the cell wall by a product of the viral gene. d. an as yet unknown mechanism. e. None of the above Answer: c Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 345 Bloom’s Category: 2. Understanding 12. The HIV virus that causes AIDS is a(n) a. arbovirus. b. double-stranded DNA virus. c. single-stranded DNA virus. d. porcine virus. e. retrovirus. Answer: e Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 346 Bloom’s Category: 1. Remembering 13. The genetic information of viruses can be a. DNA. b. RNA. c. single-stranded. d. double-stranded. e. All of the above Answer: e Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 346 Bloom’s Category: 2. Understanding 14. The influenza virus and the HIV virus differ in that only the influenza virus can a. produce and use reverse transcriptase. b. use RNA as its genetic material. c. use RNA as genetic information and mRNA without generating a DNA molecule. d. infect both horses and humans. e. All of the above Answer: c Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 346 Bloom’s Category: 2. Understanding 15. The retrovirus HIV enters a host cell a. by fusion of its envelope with the host’s plasma membrane. b. by endocytosis. c. by vectors. d. through cytoplasmic connections between cells (plasmodesmata). e. by phagocytosis. Answer: a Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 346 Bloom’s Category: 2. Understanding 16. The determination of whether a temperate phage undergoes a lytic or a lysogenic cycle depends on the a. presence or absence of protein CD4. b. two viral regulatory proteins, cI and Cro. c. presence or absence of plasmodesmata. d. nucleotide sequences of the phage. e. size of the genome. Answer: b Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 346 Bloom’s Category: 2. Understanding 17. The effects of Cro and cI on bacteriophage λ are a. competitive. b. cooperative. c. coordinate. d. inverted. e. additive. Answer: a Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 346 Bloom’s Category: 2. Understanding 18. A prokaryotic cell can control the amount of enzymes it produces by a. blocking transcription. b. hydrolyzing the mRNA after it is made. c. preventing translation of mRNA. d. hydrolyzing the protein after translation. e. All of the above Answer: e Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 348 Bloom’s Category: 2. Understanding 19. The most efficient means of regulating protein synthesis is by a. selective blocking of transcription. b. translation of the mRNA. c. inhibition of the protein. d. degradation of the protein. e. transcription of the gene. Answer: a Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 348 Bloom’s Category: 2. Understanding 20. Research on E. coli indicates that a. lactose is the preferred energy source. b. glucose is the preferred energy source. c. lactose and glucose are used equally as an energy source. d. β-galactosidase is required for glucose metabolism. e. three different proteins are synthesized when glucose is present. Answer: b Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 348 Bloom’s Category: 1. Remembering 21. When E. coli are grown in a medium with low levels of lactose, a. all the enzymes of the lactose operon are present in very small quantities. b. all the enzymes of the lactose operon are present in large quantities. c. no enzymes of the lactose operon are present. d. β-galactosidase and permease are present in small quantities, but transacetylase is present in large quantities. e. the mRNA of the lactose operon is not present at all. Answer: a Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 349 Bloom’s Category: 2. Understanding 22. 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. binds to the termination codons and allows protein synthesis to continue. Answer: b Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 349 Bloom’s Category: 2. Understanding 23. The lac operon of E. coli consists of a. a segment of DNA. b. a promoter. c. an operator. d. three structural genes. e. All of the above Answer: e Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 349–350 Bloom’s Category: 4. Analyzing 24. The three basic parts of an operon are the a. promoter, the operator, and two or more structural genes. b. promoter, the structural genes, and the termination codons. c. promoter, the mRNA, and the termination codons. d. structural genes, the mRNA, and the tRNAs. e. None of the above Answer: a Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 349–350 Bloom’s Category: 1. Remembering 25. The genes that encode repressor proteins are a. repressor genes. b. operons. c. inducer genes. d. regulatory genes. e. None of the above Answer: d Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 350–351 Bloom’s Category: 2. Understanding 26. In a repressible operon, the repressor molecule a. must first be activated by a co-repressor. 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 made negative to control the operon. Answer: a Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 351 Bloom’s Category: 2. Understanding 27. _______ acts as a co-repressor to block transcription of the tryptophan operon. a. cAMP b. Lactose c. Tryptophan d. Methionine e. CRP Answer: c Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 351 Bloom’s Category: 2. Understanding 28. It is found that 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 _______ gene regulation. a. inducible b. positive c. negative d. repressible e. positive–negative Answer: d Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 351 Bloom’s Category: 5. Evaluating 29. It is found that a certain enzyme is synthesized whenever the solution in which the cells are growing contains substance X. This phenomenon is most likely an example of _______ gene regulation. a. positive b. inducible c. repressible d. negative e. positive–negative Answer: b Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 351 Bloom’s Category: 5. Evaluating 30. 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. e. All of the above Answer: a Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 351 Bloom’s Category: 2. Understanding 31. How are inducible and repressible systems similar? a. They both control catabolic pathways. b. They both control biosynthetic pathways. c. In both systems the regulatory molecules function by binding to the operator. d. They both block transcription. e. Both systems are unique to prokaryotes. Answer: c Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 351 Bloom’s Category: 4. Analyzing 32. Catabolite repression refers to the a. increased transcription from many operons when glucose is present in the medium. b. shutdown of transcription from many operons when glucose is present in the medium. c. increased activity of inducers caused by glucose in the medium. d. Both a and b e. Both a and c Answer: b Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 351 Bloom’s Category: 2. Understanding 33. The CRP–cAMP complex binds _______ of the operon. a. close to the RNA polymerase binding site b. close to the operator c. inside one of the structural genes d. at the termination point e. None of the above Answer: a Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 351 Bloom’s Category: 4. Analyzing 34. 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. Answer: e Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 351 Bloom’s Category: 4. Analyzing 35. When the operator is unbound, the binding of the CRP–cAMP complex _______ the binding of RNA polymerase at the promoter. a. prevents b. decreases c. increases d. blocks e. All of the above are sometimes true, depending on the concentration of lactose. Answer: c Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 351 Bloom’s Category: 4. Analyzing 36. When the concentration of glucose is high, the concentration of _______ is low. a. CRP b. cAMP c. repressors d. inducers e. None of the above Answer: b Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 351 Bloom’s Category: 4. Analyzing 37. What effect does the presence of ample glucose have on the amount of lac operon transcription? a. It increases the cAMP concentration, which in turn causes a decreased rate of transcription. b. It decreases the cAMP concentration, which in turn causes an increased rate of transcription. c. It increases the rate of transcription. d. It decreases the rate of transcription. e. None of the above Answer: d Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 351 Bloom’s Category: 4. Analyzing 38. Which operon is turned “off” in response to molecules present in the environment of the cell? a. Repressible b. Suppressible c. Impressible d. Inducible e. Degraded Answer: a Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 351 Bloom’s Category: 2. Understanding 39. Gene expression can be regulated a. before transcription. b. during transcription and before translation. c. during translation. d. after translation. e. All of the above Answer: e Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 352 Bloom’s Category: 2. Understanding 40. A promoter is the region of a. a plasmid that binds the enzymes for replication. b. the mRNA that binds to a ribosome. c. DNA that binds RNA polymerase. d. the mRNA that binds tRNAs. e. None of the above Answer: c Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 353 Bloom’s Category: 1. Remembering 41. In eukaryotic cells, promoters are a. transcribed. b. transcribed and translated. c. neither transcribed nor translated. d. transcribed and then removed. e. sequences of RNA that are spliced out. Answer: c Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 353 Bloom’s Category: 4. Analyzing 42. Transcription factors are a. RNA sequences that bind to RNA polymerase. b. DNA sequences that regulate transcription. c. proteins that bind to the DNA promoter sequence. d. polysaccharides that bind to the transcripts. e. factors that bind to enhancers. Answer: c Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 353 Bloom’s Category: 2. Understanding 43. RNA polymerase II by itself cannot bind to the chromosome and initiate transcription. It can bind and act only after regulatory proteins called _______ factors have been assembled. a. translation b. posttranslation c. initiation d. transcription e. None of the above Answer: d Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 353 Bloom’s Category: 2. Understanding 44. Which of the following statements about TATA boxes is false? a. They bind a specific transcription factor. b. They are found in the region of the promoter. c. They are part of the intron consensus sequence. d. They help specify the starting point for transcription. e. They contain thymine–adenine base pairs. Answer: c Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 353 Bloom’s Category: 4. Analyzing 45. Transcription of eukaryotic genes requires a. binding of RNA polymerase to the promoter. b. binding of several transcription factors. c. capping of mRNA. d. Both a and b e. All of the above Answer: d Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 353 Bloom’s Category: 2. Understanding 46. 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. None of the above Answer: a Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 353 Bloom’s Category: 2. Understanding 47. Which of the following is a transcription factor? a. A regulatory protein b. RNA c. DNA d. Carbohydrate e. Enzyme Answer: a Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 353 Bloom’s Category: 2. Understanding 48. A DNA sequence, which can be distant from the gene, stimulates transcription when bound by a protein. This sequence is called a(n) a. TATA box. b. operon. c. enhancer. d. promoter. e. consensus sequence. Answer: c Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 353 Bloom’s Category: 2. Understanding 49. There are several proteins involved in transcription, including transcription factors, regulatory binding proteins, and activators. Their role is to tell RNA polymerase a. where to start transcribing the DNA. b. which genes to transcribe. c. where to stop transcribing the DNA. d. Both a and b e. a, b, and c Answer: d Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 353–354 Bloom’s Category: 2. Understanding 50. The different members of the β-globin gene family a. are expressed differently in different tissues. b. are expressed differently at different times of development. c. are expressed in the same way in different tissues. d. are expressed in the same way at different times of development. e. have no known function. Answer: b Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 354 Bloom’s Category: 2. Understanding 51. Which of the following statements about the globin genes is true? a. Different genes are expressed during different stages of prenatal development. b. Only one copy is functional. c. The lengths of the mRNAs are very different for different genes. d. They are the result of differential posttranscriptional splicing. e. The transcripts are longer than the coding regions. Answer: a Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 354 Bloom’s Category: 2. Understanding 52. Which of the following is not a DNA binding motif? a. Helix-straight-helix b. Helix-turn-helix c. Helix-loop-helix d. Leucine zipper e. Zinc finger Answer: a Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 354 Bloom’s Category: 2. Understanding 53. In eukaryotic cells, a negative regulator or silencer a. is made of DNA. b. binds to the enhancer region to block transcription. c. is located both upstream and downstream from the promoter. d. binds to the operator to block RNA polymerase. e. binds to a repressor protein to reduce transcription rates. Answer: e Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 354 Bloom’s Category: 2. Understanding 54. In eukaryotic cells, a positive regulator or enhancer a. binds to the enhancer region to block transcription. b. is made of RNA. c. binds to an activator protein to increase transcription rates. d. is a carbohydrate. e. is an enzyme. Answer: c Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 354 Bloom’s Category: 2. Understanding 55. 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 all genes. d. stimulates splicing of a specific mRNA. e. stimulates splicing of all mRNAs. Answer: b Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 354 Bloom’s Category: 2. Understanding 56. Which of the following statements about β-globin production is true? a. A translational repressor protein binds to the β-globin and prevents ribosomes from attaching. b. Alternative splicing of pre-mRNA results in the production of several different βglobins. c. Transcription of the β-globin gene is determined by transcription factors, regulators, enhancers, activators, silencers, and repressors. d. Ubiquitin forms a complex with the β-globin that causes its premature breakdown. e. The 5´ guanosine cap added to the mRNA is the location where RNA polymerase initiates transcription. Answer: c Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 354 Bloom’s Category: 4. Analyzing 57. The drought stress response in plants is an example of a. a transcription factor. b. coordinated gene expression. c. a way to increase water intake. d. Both a and b e. None of the above Answer: b Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 355 Bloom’s Category: 2. Understanding 58. DNA methylation a. is a mechanism of gene inactivation. b. adds methyl groups to cytosine residues in certain genes. c. inhibits transcription. d. Both a and b e. All of the above Answer: e Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 356–357 Bloom’s Category: 2. Understanding 59. DNA is wound around histones to form structures that block both the initiation and elongation steps of transcription. These structures are a. condensed chromosomes. b. lampbrush chromosomes. c. nucleosomes. d. the solenoid structure of DNA. e. 30 nm DNA fibers. Answer: c Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 357 Bloom’s Category: 2. Understanding 60. Nucleosomes disaggregate to allow transcription and then reaggregate a. through alternative splicing. b. by acetylation and deacetylation. c. through alternation of nucleotides. d. by attaching ubiquitin. e. through insertion of nucleotides. Answer: b Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 357 Bloom’s Category: 2. Understanding 61. Several types of histone modification affect gene activation and repression. Cancer cells are characterized by a greater degree of a. methylation. b. phosphorylation. c. acetylation. d. interference. e. deacetylation. Answer: e Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 357–358 Bloom’s Category: 2. Understanding 62. DNA methylation in eukaryotic chromosomes involves adding a methyl to the a. 5´ position of G. b. 5´ position of C. c. proteins bound to the DNA. d. RNA molecules. e. ribose. Answer: b Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 358–359 Bloom’s Category: 2. Understanding 63. In neurons, the globin gene contains many methylated cytosines. The globin gene, therefore, is a. expressed only in males. b. expressed only in females. c. not expressed. d. regulated by posttranscriptional control. e. regulated by posttranslational control. Answer: c Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 358–359 Bloom’s Category: 5. Evaluating 64. A cell that contains three Barr bodies will necessarily have a. three Y chromosomes. b. three X chromosomes. c. four Y chromosomes. d. four X chromosomes. e. three nucleoli. Answer: d Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 359 Bloom’s Category: 1. Remembering 65. Mary Lyon, Liane Russell, and Ernest Beutler discovered a. the basis of hormone action. b. X chromosome inactivation. c. Barr bodies. d. melanosomes. e. heterochromatin. Answer: b Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 359 Bloom’s Category: 1. Remembering 66. The Barr body is evidence for a. X chromosome inactivation. b. cell death. c. ion pumps. d. posttranslational control of eukaryotic gene expression. e. None of the above Answer: a Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 359 Bloom’s Category: 2. Understanding 67. 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 are in meiotic prophase. b. all of the chromatin in these cells is inactive. c. the DNA in these cells has replicated. d. the cells are not transcribing any genes. e. the cells came from a female rat. Answer: e Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 359 Bloom’s Category: 4. Analyzing 68. The interphase cells of normal female mammals have a stainable nuclear body called a Barr body. This body is a. an inactive X chromosome. b. made of fat droplets. c. made of fragments of mRNA. d. made of extra chromosomal pieces. e. None of the above Answer: a Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 359 Bloom’s Category: 2. Understanding 69. Heterochromatin a. contains poly A tails. b. is rarely transcribed. c. does not contain any DNA. d. is not replicated during the S phase. e. is found only in prokaryotes. Answer: b Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 359 Bloom’s Category: 2. Understanding 70. A chemical modification that adds methyl groups to cytosine residues in some genes acts to a. enhance transcription. b. amplify the gene. c. inactivate the gene. d. stabilize the mRNA. e. None of the above Answer: c Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 360 Bloom’s Category: 2. Understanding 71. 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. lithozist. e. methyl-X. Answer: a Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 360 Bloom’s Category: 1. Remembering 72. Expression of some eukaryotic genes can be regulated by translational control. One advantage of translational control is that it a. provides a means for rapid change in protein concentrations. b. prevents synthesis of excess RNA. c. directs proteins to their proper subcellular location. d. occurs only in zygotes. e. degrades proteins that are no longer needed. Answer: a Textbook Reference: 16.5 How Is Eukaryotic Gene Expression Regulated After Transcription? Page: 360 Bloom’s Category: 4. Analyzing 73. Alternative splicing helps to explain a. the small number of genes in the human genome. b. the differences in complexity among organisms. c. why there are more mRNAs than human genes. d. the great variety in proteins. e. All of the above Answer: e Textbook Reference: 16.5 How Is Eukaryotic Gene Expression Regulated After Transcription? Page: 360 Bloom’s Category: 2. Understanding 74. 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. catalytic RNA activity. d. posttranscriptional control. e. the endosymbiotic theory. Answer: d Textbook Reference: 16.5 How Is Eukaryotic Gene Expression Regulated After Transcription? Page: 361 Bloom’s Category: 2. Understanding 75. Which of the following is not a control mechanism for regulating the amount of protein synthesized in eukaryotic cells? a. Transcription regulation b. Inhibit translation with miRNAs c. Transcript processing d. Breakdown of the synthesized protein e. Stabilization of the mRNA Answer: d Textbook Reference: 16.5 How Is Eukaryotic Gene Expression Regulated After Transcription? Page: 361 Bloom’s Category: 4. Analyzing 76. 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. mitochondria c. the proteasome d. lysosomes e. the Golgi apparatus Answer: c Textbook Reference: 16.5 How Is Eukaryotic Gene Expression Regulated After Transcription? Page: 362 Bloom’s Category: 2. Understanding 77. 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. liquid hybridization. d. feedback inhibition. e. posttranslational control. Answer: e Textbook Reference: 16.5 How Is Eukaryotic Gene Expression Regulated After Transcription? Page: 362 Bloom’s Category: 2. Understanding Fill in the Blank 1. An individual viral particle is known as a(n) _______ when it is outside its host. Answer: virion Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 343 Bloom’s Category: 1. Remembering 2. The basic viral unit is the _______. Answer: virion Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 343 Bloom’s Category: 1. Remembering 3. Bacteria that house nonlytic bacteriophage are called _______ bacteria. Answer: lysogenic Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 345 Bloom’s Category: 1. Remembering 4. Bacteriophage DNA that is stably integrated into a bacterial chromosome is called a _______. Answer: prophage Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 345 Bloom’s Category: 1. Remembering 5. A _______ consists of complementary DNA transcribed from an RNA genome. Answer: provirus Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 345 Bloom’s Category: 1. Remembering 6. RNA-directed DNA synthesis is catalyzed by the viral enzyme _______. Answer: reverse transcriptase Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 346 Bloom’s Category: 1. Remembering 7. Host proteins normally bind to viral mRNA and cause the RNA polymerase to fall off the viral DNA, terminating transcription. HIV counteracts this regulation with a protein called _______ that blocks this action. Answer: Tat or transactivator of transcription Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 347 Bloom’s Category: 1. Remembering 8. The operon containing the genes for the three lactose-metabolizing proteins of E. coli is called the _______ operon. Answer: lac Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 349 Bloom’s Category: 1. Remembering 9. Genes that produce single mRNAs containing information for more than one protein are called _______. Answer: operons Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 349 Bloom’s Category: 1. Remembering 10. The site on the operon DNA where a repressor binds is called the _______ sequence. Answer: operator Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 350 Bloom’s Category: 4. Analyzing 11. In prokaryotes, _______ genes encode repressor proteins. Answer: regulatory Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 350 Bloom’s Category: 2. Understanding 12. When the synthesis of an enzyme is turned off in response to an external biochemical cue (such as an excess in tryptophan), the enzyme is said to be _______. Answer: repressible Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 350 Bloom’s Category: 2. Understanding 13. Genes that specify the primary structure of a protein are called _______ genes. Answer: structural Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 350 Bloom’s Category: 1. Remembering 14. A positive control process that relies on increasing the affinity of promoters for RNA polymerase is called _______. Answer: catabolic repression Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 351 Bloom’s Category: 2. Understanding 15. The region of the gene that binds RNA polymerase is the _______. Answer: promoter Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 352 Bloom’s Category: 1. Remembering 16. Changes in the expression of a gene or set of genes that occur without changing the DNA sequence is referred to as _______. Answer: epigenetics Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 356 Bloom’s Category: 1. Remembering 17. Heavily methylated genes tend to be _______ (active or inactive). Answer: inactive Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 356 Bloom’s Category: 2. Understanding 18. DNA in eukaryotes is wrapped around special proteins to form structures that look like beads on a string. These structures are called _______. Answer: nucleosomes Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 357 Bloom’s Category: 1. Remembering 19. In a stained preparation of epithelial cells from a female mammal, the highly condensed chromosome observable in interphase nuclei is the inactive X chromosome, or _______. Answer: Barr body Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 359 Bloom’s Category: 1. Remembering 20. _______ syndrome is due to genomic imprinting. If the male region on chromosome 15 is deleted, the baby develops a phenotype marked by muscle weakness and obesity. Answer: Prader–Willi Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 359 Bloom’s Category: 2. Understanding Diagram 1.–3. Refer to the diagram below. 1. From the diagram it can be concluded that a. each transcription factor has specific binding sites. b. transcription factors bind directly to DNA. c. TFIID binds to the promoter at the TATA box after B and F have altered its shape. d. protein-coding genes contain noncoding sequences. e. RNA polymerase II binds to the promoter and initiates transcription. Answer: a Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 353 Bloom’s Category: 4. Analyzing 2. The only transcription factor(s) that bind(s) directly to DNA is/are a. B. b. F. c. E and H d. TFIID e. B and H. Answer: d Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 353 Bloom’s Category: 4. Analyzing 3. Which of the following represents the regulatory sequence of the DNA? a. TATAT b. ATATA c. TFIID d. BFEH e. TFIID + B Answer: a Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 353 Bloom’s Category: 4. Analyzing STUDY GUIDE QUESTIONS (By Nancy Guild) Knowledge and Synthesis 1. Viruses consist of a. a protein core and a nucleic acid capsid. b. a cell wall surrounding nucleic acid. c. RNA and DNA enclosed in a membrane. d. a nucleic acid core surrounded by a protein capsid, and in some cases, a membrane. e. a nucleic acid core surrounded by a cell membrane. Answer: d Feedback: Nucleic acids do not form capsids; cell walls are found in bacterial and plant cells, not viruses. Viruses are organized so that the nucleic acid is surrounded by protein (not membranes), and a membrane may surround the protein capsid. Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 343 2. Lytic bacterial viruses a. infect the cell, replicate their genomes, and lyse the cell. b. infect the cell, replicate their genomes, transcribe and translate their genes, and lyse the cell. c. infect the cell, replicate their genomes, transcribe and translate their genes, package those genomes into viral capsids, and lyse the cell. d. infect the cell, transcribe and translate their RNA, replicate their genomes, package those genomes into viral capsids, and lyse the cell. e. insert their chromosome into the host chromosome. Answer: d Feedback: This sequence includes the most complete details of the viral life cycle. Viral transcription and translation have to occur first so that viral gene products needed for viral replication will be synthesized. Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 343–345 3. Animal viruses that integrate their DNA into the host chromosome a. have DNA as their genome. b. are prophages. c. copy their RNA genome into DNA using reverse transcriptase. d. replicate their genome using RNA polymerase. e. can undergo only a lytic infection cycle. Answer: c Feedback: Answer b describes a provirus, which is a bacterial virus that has inserted its genome into a host chromosome. Animal viruses replicate their RNA genomes using reverse transcriptase and do not lyse the cells they infect. Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 343 4. An operon a. is regulated by a repressor binding at the promoter. b. has structural genes that are all transcribed from same promoter. c. has several promoters, but all of the structural genes are related biochemically. d. is a set of structural genes that are all under the same translational regulation. e. is transcribed when RNA polymerase binds the operator. Answer: b Feedback: An operon is a set of genes that are all transcribed from the same promoter, which is the site where RNA polymerase binds. The repressor binds at the operator site, which overlaps the promoter. Answer d is not correct because the operon is regulated transcriptionally, not translationally. Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 349 5. If the gene encoding the lac repressor is mutated so that the repressor can no longer bind the operator, will transcription of that operon occur? a. Yes, because the repressor transcriptionally activates the lac genes. b. Yes, but only when lactose is present. c. No, because RNA polymerase is needed to transcribe the genes. d. Yes, because RNA polymerase will be able to bind the promoter and transcribe the operon. e. No, because cAMP levels are low when the repressor is nonfunctional. Answer: d Feedback: If the lac repressor is nonfunctional, it cannot bind the operator site, and transcription of the lac operon will occur at all times, whether or not lactose is present. Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 350–351, Figure 16.11 6. If the gene encoding the trp repressor is mutated such that it can no longer bind tryptophan but can still bind the operon, will transcription of the trp operon occur? a. Yes, because the trp repressor can bind the trp operon and block transcription only when it is bound to tryptophan. b. No, because this mutation does not affect the part of the repressor that can bind the operator. c. No, because the trp operon is repressed only when tryptophan levels are high. d. Yes, because the trp operon can allosterically regulate the enzymes needed to synthesize the amino acid tryptophan. e. No, because the repressor will be continuously bound to the operator. Answer: a Feedback: If the repressor can no longer bind tryptophan, then it cannot bind the operator, and transcription of the trp operon will always be on, whether tryptophan levels in the cell are high or low. Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 351 7. Transcriptional regulation in prokaryotes can occur by a. a repressor binding an operator and preventing transcription. b. an activator binding upstream from a promoter and positively affecting transcription. c. different promoter sequences binding RNA polymerase more tightly, resulting in more effective transcriptional initiation. d. the control of promoter efficiency. e. All of the above Answer: e Feedback: Answer a refers to the lac and trp repressors, answer b to the CRP protein, and answer c to promoters that have different transcriptional efficiencies. Answer d refers to the lac operon. Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 348–350 8. For the bacteriophage λ, the “decision” to become a prophage is made a. if environmental resources (e.g., food) for the host are limited. b. when the Cro protein binds the promoter. c. when the cI protein binds the promoter. d. when bacterial lysis occurs. e. at the end of the lytic infection. Answer: c Feedback: The “decision” to become a prophage by bacteriophage λ is made when cI binds the promoter early in infection. This decision is made if the host is experiencing rich nutrient conditions and results in lysogeny, not cell lysis. Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 346 9. Imagine that the TATA box for gene X becomes highly methylated. How will this affect the expression of gene X? a. There will be no effect. b. Gene X will be transcribed but not translated. c. Gene X will be transcribed if the transcription factors receive the appropriate environmental signal. d. Gene X will not be transcribed or translated. e. Gene X will be transcribed if the histones become acetylated. Answer: d Feedback: Gene X will not be transcribed or translated, since methylation sites on DNA are transcriptionally inactive. Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 356–357 10. Imagine that gene X is moved to a part of the chromosome where the histones are highly acetylated. How will this affect its expression? a. There will be no effect. b. It will be transcribed but not translated. c. It will be transcribed if the transcription factors receive the appropriate environmental signal. d. It will not be transcribed or translated. e. It will be transcribed if the histones become deacetylated. Answer: d Feedback: Acetylation leads to loosening of the nucleosomes, resulting in more DNA sequence being accessible for transcription. If transcription factors receive the appropriate environmental signal, transcription will occur. Deacetylation leads to tighter packing of the nucleosomes. Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 357–358 11. Which of the following is an example of regulation of eukaryotic transcription? a. Iron binding the repressor protein for the ferritin mRNA and increasing ferritin expression b. Proteostome breakdown of protein–ubiquitin complexes c. MicroRNAs binding their target mRNA and causing its degradation d. Alternate splicing of an mRNA transcript e. Activator proteins binding an enhancer Answer: e Feedback: Answer a refers to translational regulation; answer b refers to the regulation of protein longevity; answers c and d refer to posttranscriptional regulation. Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 352 12. Which of the following statements about histone modifications is false? a. They cause some genes to be transcriptionally activated. b. They can result in the repression of gene transcription. c. They are inherited from parental cells in a Mendelian fashion. d. They cause Barr bodies to form. e. All of the above are false. Answer: d Feedback: Histone modifications are inherited in a non-Mendelian fashion. Depending on the parent in which the modification (genomic imprinting) occurs (i.e., Angelman syndrome versus Prader–Willi), the resulting phenotype can be different, even though the genotype is the same. Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 357–358 13. What would happen initially to cells that lack a functional ubiquitin? a. Nothing would happen. b. Transcriptional initiation would increase. c. Protein degradation would decrease. d. Histone modifications would increase. e. Translation of proteins would be more efficient. Answer: c Feedback: In the absence of ubiquitin, protein degradation would decrease, since ubiquitin targets proteins for degradation in the proteasome Textbook Reference: 16.5 How Is Eukaryotic Gene Expression Regulated After Transcription? Page: 362 14. Which of the following would not affect gene expression in a eukaryotic cell? a. Deletion of a promoter b. Deletion of an enhancer c. Lack of modification of the cap structure on mRNA. d. Inability of transcription factor to bind promoter e. Deletion of a DNA ori site Answer: e Feedback: Deletion of an ori site on a eukaryotic chromosome would affect DNA replication, not transcription. All of the other alterations would affect transcription. Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 352–356 15. Transcription factors a. have a particular motif that allows them to interact with mRNA. b. assemble at the promoter to help translation begin. c. mark particular proteins for degradation. d. interact with RNA polymerase to initiate transcription. e. help stabilize the mRNAs in the cytoplasm. Answer: d Feedback: Transcription factors interact with RNA polymerase to help transcriptional (not translational) initiation. They do have particular protein motifs, but they bind DNA, not RNA. They do not stabilize mRNAs in the cytoplasm, or mark proteins for degradation. Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 353–355 Application 1. Animal viruses are termed obligate parasites. What is the meaning of this term? Answer: Animal viruses cannot express their genes, replicate their genomes, or multiply unless they are in the cytoplasm of the host cell. They use the host cell’s components (ribosomes, ATP) to grow and reproduce. Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 343 2. Why are antibiotics useless in combating animal viral infections? Answer: Most antibiotics attack bacterial cells by inhibiting prokaryotic translation. Animal viruses use the host translation machinery, which is different enough from the bacterial translation machinery to be unaffected by antibiotics. Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 346–348 3. Suppose that a cell has a mutation that deletes the gene encoding the repressor for a certain operon, and a plasmid is introduced into the host cell that carries a wild-type copy of the gene for the repressor. Is normal regulation of this operon restored in the presence of this plasmid? Answer: Yes. The repressor gene can be transcribed and translated from the plasmid DNA, and normal regulation will be restored. Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 349–351 4. Suppose that a cell has a mutation that deletes the gene encoding the operator for a certain operon, and a plasmid is introduced into the host cell that carries a wild-type copy of the operator. Is normal regulation of this operon restored in the presence of this plasmid? Answer: No. The operator site on the plasmid cannot restore regulation unless it recombines with the host operator site in such a way that it replaces the mutant operator on the host chromosome. The DNA site on the plasmid would bind repressor, but because that site is not adjacent to the promoter or the structural genes on the chromosome, normal regulation of those genes cannot occur. Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 349–351 5. Suppose you are engineering gene Y, such that when it is inserted into a eukaryotic chromosome it will be expressed continuously. Which specific sequences must be part of this gene so that it will be expressed? Answer: You will need a promoter that binds transcription factors (such as a TATA box), an RNA polymerase, and regulatory binding sites that bind activator proteins. You will also need to put it into a chromosomal region that has not been silenced by condensed nucleosomes. Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 353–354 6. Suppose that you are engineering a new plant in which gene Y will be activated under drought conditions. What kinds of DNA sequences need to be present to ensure activation of the gene under these conditions? Answer: The plant will need stress response elements (SREs) in front of the promoter for gene Y. SREs are bound by transcription factors that are sensitive to drought, and genes with SRE sequences in front of their promoters can be coordinately regulated. Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 355–356 TEXTBOOK SELF-QUIZ 1. Which of the following statements about the lac operon is not true? a. When lactose binds to the repressor, the repressor can no longer bind to the operator. b. When lactose binds to the operator, transcription is stimulated. c. When the repressor binds to the operator, transcription is inhibited. d. When lactose binds to the repressor, the shape of the repressor is changed. e. The repressor has binding sites for both DNA and lactose. Answer: b 2. Which of the following is not a type of viral reproduction? a. DNA virus in a lytic cycle b. DNA virus in a lysogenic cycle c. DNA virus (single-stranded) with a double-stranded DNA intermediate d. RNA virus with reverse transcription to make cDNA e. RNA virus acting as tRNA Answer: e 3. In the lysogenic cycle of bacteriophage λ, a. a repressor, cI, blocks the lytic cycle. b. the bacteriophage carries DNA between bacterial cells. c. both early and late phage genes are transcribed. d. the viral genome is made into RNA, which stays in the host cell. e. many new viruses are made immediately, regardless of host health. Answer: a 4. An operon is a. a molecule that can turn genes on and off. b. an inducer bound to a repressor. c. a series of regulatory sequences controlling transcription of protein-coding genes. d. any long sequence of DNA. e. a promoter, an operator, and a group of linked structural genes. Answer: e 5. Which of the following is true of both positive and negative gene regulation? a. They reduce the rate of transcription of certain genes. b. They involve regulatory proteins (or RNA) binding to DNA. c. They involve transcription of all genes in the genome. d. They are not both active in the same organism or virus. e. They act away from the promoter. Answer: b 6. In DNA, 5-methylcytosine a. forms a base pair with adenine. b. is not recognized by DNA polymerase. c. is related to transcriptional silencing of genes. d. does not occur at promoters. e. is an irreversible modification of cytosine. Answer: c 7. Which statement about selective gene transcription in eukaryotes is not true? a. Regulatory proteins can bind at a site on DNA distant from the promoter. b. Transcription requires transcription factors. c. Genes are usually transcribed as groups called operons. d. Both positive and negative regulation occur. e. Many proteins bind at the promoter. Answer: c 8. Control of gene expression in eukaryotes includes all of the following except a. alternative RNA splicing. b. binding of proteins to DNA. c. transcription factors. d. stabilization of mRNA by miRNA. e. DNA methylation. Answer: d 9. The promoter in the lac operon is a. the region that binds the repressor. b. the region that binds RNA polymerase. c. the gene that codes for the repressor. d. a structural gene. e. an operon. Answer: b 10. Epigenetic changes a. can involve DNA methylation. b. are due to nonhistone protein acetylation. c. are due to changes in the genetic code. d. are an example of positive control of translation. e. are never reversible. Answer: a BIOPORTAL DIAGNOSTIC QUIZ (Personalized Study Plan Quiz) (By Richard McCarty) 1. Bacterial viruses (phage) a. can reproduce on their own. b. require a host cell to replicate. c. carry out metabolism. d. have a plasma membrane. e. are alive. Answer: b Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 344 Bloom’s Category: 2. Understanding 2. Regulation of gene expression during the phage lytic cycle does not include a. binding of a host RNA polymerase to a viral promoter. b. stimulation of viral late gene transcription. c. enhancement of the host’s gene transcription. d. enhancement of viral early gene transcription. e. down regulation of the host’s gene transcription. Answer: c Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 344–345 Bloom’s Category: 2. Understanding 3. The process by which some phage may transfer DNA fragments from one bacterium to another is called a. transformation. b. induction. c. lysogeny. d. transduction. e. transfection. Answer: d Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 345 Bloom’s Category: 1. Remembering 4. During lysogeny a. the viral DNA is present as a self-replicating plasmid. b. the host bacterium is usually adversely affected. c. the host’s gene expression is inhibited. d. the viral DNA is lost in a few generations. e. the viral genome is integrated into the host’s genome. Answer: e Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 345–340 Bloom’s Category: 2. Understanding 5. The switch from lysogeny to lysis in phage λ (lambda) a. involves two proteins that act either as activators or repressors of the expression of specific genes. b requires host gene expression. c. occurs when the host is growing poorly. d. uses host promoters. e. Both a and c Answer: e Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 345–346 Bloom’s Category: 2. Understanding 6. A herpes virus causes both chicken pox and shingles in humans. People who have had chicken pox may be afflicted with shingles much later in life. What is a likely explanation for this? a. The intact virus was harbored within cells and was activated. b. The viral DNA had been incorporated into the host’s genome and was induced to enter the lytic cycle. c. The viral DNA became active while integrated into the host’s DNA. d. Expression of host DNA genes was shut down. e. All of the above Answer: b Textbook Reference: 6.1 How Do Viruses Regulate Their Gene Expression? Page: 346 Bloom’s Category: 4. Analyzing 7. A retrovirus a. has a double-stranded DNA genome. b. has a single-stranded DNA genome. c. has a double-stranded RNA genome. d. encodes a reverse transcriptase. e. integrates its genome directly into the host’s genome. Answer: d Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 346 Bloom’s Category: 4. Analyzing 8. Retroviruses and RNA viruses differ in that a. the viral genome of RNA viruses is translated directly by the host cell ribosomes. b. a cDNA copy of the RNA virus genomes is made. c. retroviruses often enter the lytic phase. d. retroviruses do not have an RNA genome. e. RNA viruses are often lysogenic. Answer: a Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 346 Bloom’s Category: 4. Analyzing 9. The enzyme, reverse transcriptase, a. is absent in the assembled HIV. b. is coded for by a gene in the host’s genome. c. does not require a template. d. is present in the assembled HIV. e. is needed for the replication of all RNA viruses. Answer: d Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 346–347 Bloom’s Category: 4. Analyzing 10. Which one of the statements given below about the HIV envelope is false? a. The envelope contains glycoproteins. b. The envelope contains phospholipids. c. The envelope surrounds the capsid. d. The envelope fuses with the plasma membrane during entry of the virus into a cell. e. Reverse transcriptase is in the envelope. Answer: e Textbook Reference: 16.1 How Do Viruses Regulate Their Gene Expression? Page: 346–347 Bloom’s Category: 2. Understanding 11. Structural genes a. code for structural proteins. b. are regulatory regions of DNA. c. specify the primary structure (amino acid sequence) of proteins. d. are always constitutively expressed. e. are absent in eukaryotes. Answer: c Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 349 Bloom’s Category: 1. Remembering 12. Operons a. are common in eukaryotes. b. consist of structural genes only. c. consist of a promoter, an operator, and two (or more) structural genes. d. consist of a promoter, an operator, structural genes, and a repressor gene. e. include inducer genes. Answer: c Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 349–350 Bloom’s Category: 1. Remembering 13. The expression of the lac structural genes is _______ when lactose is absent from the culture medium and is _______ when lactose is added because lactose binds to the _______ and inactivates it. a. low; high; lac repressor b. high; low; lac inducer c. low; high; lac promoter d. high; low; lac operator e. low; high; lac operator Answer: a Textbook Reference: 16.2 How Is Gene Expression Regulated in Prokaryotes? Page: 350 Bloom’s Category: 2. Understanding 14. Prokaryotes and eukaryotes differ in transcription in that a. there are three RNA polymerases in eukaryotes. b. initiation of transcription is simpler in prokaryotes. c. structural genes for a pathway are more likely to be clustered in prokaryotes. d. eukaryotic promoters have a TATA box. e. All of the above Answer: e Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 353 Bloom’s Category: 1. Remembering 15. In gene transcription of structural genes, initiation in eukaryotic _______ cannot bind directly to the _______. Initiation requires _______ and other regulatory proteins called “_______.” a. RNA polymerase I; initiation site; TFIID; transcription factors b. RNA polymerase II; initiation site; TFIID; transcription factors c. RNA polymerase III; initiation site; TFIID; initiation factors d. RNA polymerase I; TATA box: initiation factors; TFIID e. TFIID; RNA polymerase I; initiation site; transcription factors Answer: b Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 353–354 Bloom’s Category: 2. Understanding 16. Common structural motifs for transcription factors with specific DNA binding domains do not include a. helix-loop-helix. b. helix-turn-helix. c. zinc finger. d. -pleated sheet. e. leucine zipper. Answer: d Textbook Reference: 16.3 How Is Eukaryotic Gene Transcription Regulated? Page: 354 Bloom’s Category: 1. Remembering 17. Epigenetics is defined as changes in the expression of a gene or set of genes by _______ and _______. a. transcription factors; DNA methylation b. chromosomal protein alteration; transcription factors c. DNA methylation; chromosomal protein alteration d. promoters; DNA methylation e. promoters; chromosomal protein alteration Answer: c Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 356 Bloom’s Category: 1. Remembering 18. DNA methylation a. is important in the development of mammalian embryos. b. may repress the transcription of genes. c. can play a role in some cancers. d. is abundant in promoters. e. All of the above Answer: e Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 356–357 Bloom’s Category: 1. Remembering 19. The DNA methylation pattern in sperm differs from that in eggs. The transcription of the gene that is methylated in eggs would be _______, whereas that of its unmethylated counterpart in sperm would be _______. This phenomenon is called “_______.” a. high; low; DNA footprinting b. low; high; genomic imprinting c. high; low; genomic imprinting d. low; high; genetic imprinting e. high; low; genetic imprinting Answer: b Textbook Reference: 16.4 How Do Epigenetic Changes Regulate Gene Expression? Page: 358 Bloom’s Category: 2. Understanding 20. Which of the following mechanisms of posttranscriptional regulation of gene expression can produce several different proteins from a single gene? a. MicroRNAs b. Protein degradation c. Protein phosphorylation d. Alternative splicing e. Regulation of translation Answer: d Textbook Reference: 16.5 How Is Eukaryotic Gene Expression Regulated After Transcription? Page: 360–361 Bloom’s Category: 1. Remembering