1.Please describe 4 ways to repair thymidine dimer in E. coli. 2.Diagram the event in post-replication recombination-mediated repair of following DNA damage. Please describe the enzymes used and their job. 3.How does a retrovirus solve the replication of linear ends of its genome. 4.Define the two term “processivity” and “fidelity” in DNA replication. What proteins or enzymatic activities increase each of these during E. coli replication? 5.What lambda phage genes are important for lytic cycle in middle phase? What are important for lysogenic cycle? 6.What is “operon” in prokaryotes? What is the main difference between a prokaryotic mRNA from an operon and a typical eukaryotic mRNA? 7.Draw a diagram to describe the features of a prokaryotic promoter. What is the role of these features in transcription? 8.A DNA polymerase holoenzyme comprises several subunits (complexes). How do these subunit form (please draw a holoenzyme) and what is the specific function of these in DNA replication? 9.Gene regulation in prokaryotic transcription is dependent on initiation and termination. What cis-acting and trans-acting elements take place in these two stages? 10.Bacterial RNA polymerase consists of core enzyme and sigma factor. What is the role of the sigma factor in transcription? 11.Small RNAs have been shown to play an important role in term of gene expression. Please briefly describe two examples. 12.What is the basic mechanism of “attenuation” in gene expression? Please describe an example how translation control this event. 13.What ways to solve the ends of linear DNA in replication? 14.Please draw a scheme to describe the machineries participating in DNA synthesis in both continuous and discontinuous orientations. 15.How a prokaryotic origin (for example, oriC) is created the replication fork during the initiation stage of DNA replication? Name the enzymes used and their functions. 16.Please explain the possible regulatory mechanism of methylation/hemimethylation in origin initiation. 17.What is the significance of transposons and/or retroposons in our genome? 18.In a brief essay, compare and contrast the genetic regulation of metabolic pathways by answering the following questions in two paragraphs. a) Briefly define an anabolic pathway and give an example in E. coli. Is an anabolic pathway usually regulated by the concentration of the substrate or the product? If an anabolic pathway is regulated by a repressor, would the repressor be turned on or turned off in the presence of excess substrate/product? Why does this make sense energetically? b) Briefly define a catabolic pathway and give an example in E. coli. Is a catabolic pathway usually regulated by the concentration of the substrate or the product? If a catabolic pathway is regulated by a repressor, would the repressor be turned on or turned off in the presence of excess substrate/product? Why does this make sense energetically? 19.Explain what the phenotype Lac– means. 20.For each of the enzymes or enzymatic activities involved in replication (below), give the function of that enzyme IN THREE WORDS OR LESS. Example: DNA gyrase Answer: Relieves supercoiling A) 3' > 5' exonuclease activity of DNAP I B) 5' > 3' exonuclease activity of DNAP I C) DNA helicase D) DNA ligase E) n' protein F) SSB 21.In a brief essay, describe the transcriptional regulation of the Lac operon. In your answer, you MUST include: lac operon (e.g. lacZ, lacY, lacA), LacI, Crp-cAMP complex, glucose, lactose, repression, activation. 22.Refer to the drawing below to answer of the following questions. U U A A C-G--- G-C | A-U | １ G-C | G-C--- AGAAGC-GUUUUUUUU | | --------- ２ What is the probable function of this section of RNA? How does part #1 (the stem-loop) affect transcription? (Be specific) How does part #2 affect transcription? (Be specific) On the drawing below, LABEL all of the parts of this prokaryotic polycistronic mRNA. Remember, this is a mRNA, NOT DNA. -- 我：听过真月谭月姬吗？ 友：什麽？筝越弹越激？ --

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