分子生物学资料：Chapter6_Questions

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1、 2014 Pearson Education, Inc.Chapter 6课后作业2014-11-17 2014 Pearson Education, Inc.1. Under which set of conditions does the lac operon in E. coli produce high levels of lacZ, lacY, and lacA transcripts?A. in the presence of lactose and absence of glucoseB. in the presence of both lactose and glucoseC

2、. in the absence of both lactose and glucoseD. in the absence of lactose and presence of glucose 2014 Pearson Education, Inc.2. In prokaryotes, when can basal level (constitutive) expression of a gene occur?A. only when an activator bindsB. when an activator and repressor bindC. in the absence of ac

3、tivator and repressor bindingD. only if the expression of the gene is regulated by a repressor 2014 Pearson Education, Inc.3. You create an E. coli mutant that has a two bp deletion between the 10 and 35 elements of the merT promoter. In the absence of mercury, which of the following outcomes do you

4、 expect?A. expression of merT, but only in the presence of the activator MerRB. no expression of merTC. constitutive expression of merTD. expression of merT, but only in the presence of the activator MerR 2014 Pearson Education, Inc.4. Which one of the following statements is false regarding the rol

5、e of repressor in the regulation of phage transcription?A. repressor bound to DNA excludes RNA polymerase.B. repressor cooperatively binds DNA.C. repressor lacks an activation domain.D. repressor recruits RNA polymerase to the promoter. 2014 Pearson Education, Inc.5. Which of the following statement

6、s is true regarding cooperative binding? A. It decreases the concentration of protein required to fill adjacent protein binding sites on DNA.B. It increases the concentration of protein required to fill adjacent protein binding sites on DNA.C. It decreases the affinity of a protein for its correct b

7、inding site on DNA.D. It is observed only in DNA-binding proteins. 2014 Pearson Education, Inc.6. AraC and CAP both regulate transcription of the araBAD operon. Which statement best describes the role of these two proteins in the presence of arabinose and the absence of glucose?A. Both AraC and CAP

8、are inducers of transcription.B. Both AraC and CAP are repressors of transcription.C. AraC is a repressor of transcription, while CAP is an inducer of transcription.D. AraC is an inducer of transcription, while CAP is a repressor of transcription. 2014 Pearson Education, Inc.7. Which of the followin

9、g would be true of gal gene expression if a mutation inhibited binding of GalR to the operator of the gal operon? A. The gal genes would be basally expressed only in the absence of glucose.B. The gal genes would be fully expressed only in the presence of glucose.C. The gal genes would not be express

10、ed.D. The gal genes would be fully expressed only in the absence of glucose. 2014 Pearson Education, Inc.Question 8. The most common level of regulation of gene expression occurs at transcription initiation. Explain why.Question 9. Provide three examples of allosteric regulation from this chapter.Qu

11、estion 10. List three mechanisms for transcriptional repression in prokaryotes and in each case an example of a protein that uses the mechanism.Question 11. Describe how alternative factors play a role in the regulation of transcription in prokaryotes. 2014 Pearson Education, Inc.Question 12. Given

12、the following mutants and conditions, predict the expression of the of the lacZ gene (no expression, basal level of expression, or activated level of expression).A. A mutant of E. coli that has a mutation in the operator of the lac operon that prevents the repressor from bindinga. In the presence of

13、 glucose, absence of lactoseb. In the presence of glucose, presence of lactosec. In the absence of glucose, absence of lactosed. In the absence of glucose, presence of lactoseB. A mutant of E. coli that has a mutation in the promoter of the lac operon (for the lacZ, lacY, and lacA genes) that prevents RNA polymerase from bindinga. In the presence of glucose, absence of lactoseb. In the presence of glucose, presence of lactosec. In the absence of glucose, absence of lactosed. In the absence of glucose, presence of lactose