Genetics - Chapter 15 Review

Chapter 15 Review 1. Which term would be applied to a regulatory condition that occurs when protein is associated with a particular section of DNA and greatly reduces transcription? Negative control 2. Which term is used to describe enzymes that are produced only when specific substrates are present in the environment? Inducible 3. Certain mutations in the regulator gene of the lac system in E. coli result in maximal synthesis of the Lac proteins (β-galactosidase, etc.) even in the absence of the inducer (lactose). Provide an explanation for this observation. If there is a mutation in either the repressor gene or the operator binding site, translation will continue. A mutation in the repressor gene will either make a non-functional repressor protein or not make one at all. A mutation in the operator binding site will not allow the repressor protein to bind. Both of these situations mean the polymerase can bind even in the absence of lactose. 4. Which term refers to a contiguous genetic complex that is under coordinated control? Operon 5. In the lac operon, the product of structural gene lacZ is capable of ________. Splitting the β-linkage of lactose 6. For each region of the lac operon on the F' plasmid, I+ P+ Oc Z− Y+ , determine whether the region is wild type (that is, it produces a functional protein or it's a correct protein binding sequence) or whether the region is mutated. The promoter sequence is correct/functional. The repressor protein is produced. Permease is produced from the lacY gene. 7. Use the information from Part A to determine how the operon is regulated for this genotype (I+ P+ Oc Z− Y+ ). Operon is constitutive; permease is produced even when lactose is absent. 8. Now, for each region of the lac operon on the bacterial chromosome, I− P+ O+ Z+ Y−, determine whether the region is wild type (that is, it produces a functional protein or it's a correct protein binding sequence) or whether the region is mutated. The promoter sequence is correct/functional. The operator sequence is correct/functional. Beta-galactosidase is produced from the lacZ gene. 9. Use the information from Part C to determine how the operon is regulated for this genotype (I- P+ O+ Z+ Y-). Operon is constitutive; lacZ is transcribed even when lactose is absent. 10. For the partial diploid you've created, F' I+ P+ Oc Z− Y+ / I− P+ O+ Z+ Y− , you already know that the promoter sequences for copies are functional, so you can focus on the repressor proteins and operator regions that control expression. 11. Which of the following summarizes expression of the lac genes in this partical diploid: I+ P+ Oc Z− Y+ / I− P+ O+ Z+ Y− ? Permease is made both in the presence of and in the absence of lactose; betagalactosidase is only made when lactose is present. 12. Which of the following terms best characterizes catabolite repression associated with the lac operon in E. coli? Positive Control 13. Lactose is an inducer of the lac operon. True 14. What would be the effect of a mutation in the lacI gene that prevented the repressor from binding to lactose? The lac Z, Y, and A genes would not be expressed. 15. What is the role of glucose in catabolite repression? It decreases the levels of cAMP in the cell, repressing transcription from the lac operon. 16. Which of the following statements best describes the trp operon? It is repressible and under negative control. 17. When referring to attenuation in regulation of the trp operon, it would be safe to say that when there are high levels of tryptophan available to the organism, ________. transcriptional termination is likely 18. What is a riboswitch? A form of gene regulation based on secondary structure of mRNA sequences present in the 5'UTR. 19. Attenuation involves the termination of mRNA synthesis. True 20. What is the function of the terminator hairpin loop in the mRNA transcript produced by the trp operon? The terminator hairpin causes transcription to stop. 21. Regarding eukaryotic and prokaryotic genetic regulation, what process seems to be the most similar between the two? Transcriptional regulation 22. Regulation of RNA transport through the nuclear membrane is as common in prokaryotes as in eukaryotes. False 23. DNA methylation may be a significant mode of genetic regulation in eukaryotes. Methylation refers to ________. Addition of methyl groups to the cytosine of CG doublets 24. Which of the following clusters of terms applies when addressing enhancers as elements associated with eukaryotic genetic regulation? Cis-acting, variable orientation, variable position 25. Two modular elements that appear as consensus sequences upstream from RNA polymerase II transcription start sites are ________. TATA and CAAT 26. Which of the following elements function specifically in eukaryotic transcription and gene expression? Promotors and enhancers 27. Which of the following statements about the positive control of gene expression are true? The regulatory molecule needs to be provided to the DNA for transcription to occur. The regulatory molecule stimulates transcription. 28. Which of the following statements about the negative control of gene expression are true? The regulatory molecule interferes with transcription The regulatory molecule needs to be removed from the DNA for transcription to occur. 29. Which of the following statements about the inducible system are true? The repressor is inactivated by an inducer, thus permitting transcription. The repressor normally interacts with the operator to inhibit transcription. 30. Which of the following statements about the repressible system are true? The repressor is normally inactive. The repressor is activated by the corepressor, binds to the operator and inhibits transcription 31. Compare and contrast the specific mechanisms in these two types of regulation. 32. Sort the genotypes into the appropriate categories. 33. Drag the terms on the left to the appropriate blanks on the right to complete the sentences. 34. The main purpose of a probe is its insertion in plasmid DNA. False 35. The function of a ddNTP in DNA sequencing is to methylate guanine. False 36. DNA sequencing by the Sanger method employs which of the following for chain termination? Dideoxynucleotides 37. What techniques can scientists use to determine if a particular transgene has been integrated into the genome of an organism? Use of reporter genes