2b) Suppose you generated a mutant E. coli strain in which it was DNA Polymerase I that was inactivated - assuming that all the other enzymes involved in replication remained fully functional, how would DNA replication in these mutant cells lacking DNA Pol I differ from DNA replication in normal E. coli? Briefly explain why you would expect to see that change/those changes in DNA replication in the mutant cells.

2b) Suppose you generated a mutant E. coli strain in which it was DNA Polymerase I that was inactivated - assuming that all the other enzymes involved in replication remained fully functional, how would DNA replication in these mutant cells lacking DNA Pol I differ from DNA replication in normal E. coli? Briefly explain why you would expect to see that change/those changes in DNA replication in the mutant cells.

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter28: Dna Metabolism: Replication, Recombination, And Repair

Section: Chapter Questions

Problem 22P

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For each DNA repair process in column I, list all characteristics fromcolumn II that correctly describe that process.I(a) Nucleotide excision repair(b) Photoreactivation(c) Base excision repair(d) Recombinational repair(e) SOS-driven error-prone repair(f) Alkyltransferase repair(g) Mismatch repair(h) Double-strand break repairII1. RecA protein participates.2. Damaged nucleotides are removed by nick translation.3. A free radical mechanism is involved.4. The repair enzyme functions only once.5. The key enzyme contains a bound folate cofactor.6. No bases or nucleotides are removed from the DNA.7. Deficiency of this enzyme in humans greatly increases the risk of skincancer.8. This system is chiefly responsible for the mutagenic effect of ultravioletlight.9. This process begins with cleavage of two phosphodiester bonds.10. This process begins up to 1 kbp away from the site to be repaired.11. DNA ligase catalyzes the final reaction.12. This process also occurs in meiotic recombination.13.…
You examine DNA replication in an E. coli mutant, which has a partially defective DNA polymerase. In vitro experiments using the mutant DNA polymerase gives an error rate of 10-3, as compared to the expected error rate of 10-6. Which of the following activities is the mutant polymerase likely to be missing, as compared to the normal polymerase? Explain your answer.
During high stress environments, it has been found that some bacteria activate a genetic mechanism that allows them to incorporate more mutations into the DNA during replication. Would the following two enzymes be impacted by such a mechanism? (i)DNA polymerase IIIii) Helicase
a) "Out of three E.coli DNA polymerases, DNA polymerases 3 has a high processivity and rate of polymerization and therefore better suited for replication of the genome" What is meant by processivity? how does the DNA polymerase 3 maintain high processivity? b) What is a replication fork ?. Give the protein/enzymes of a replication fork and describe their function?
. Which of the following statements best describe the mismatch repair pathway?a. It is part of the 3′to 5′proofreading function of DNApolymerase.b. It acts after DNA replication by recognizing mismatched base pairs.c. It is activated by stalled replication forks.d. It is coupled to transcription.
Extreme UV exposure leads to the SOS response in bacteria. By what mechanism does the SOS response function? Answer choices induction of photolyase and the addition of white light to remove the thymine dimer destruction of lexA, which leads to expression of an alternate, error-prone DNA polymerase homologous recombination repair non-homologous end joining exinuclease removal of a segment of DNA including a thymine dimer, followed by the replacement of DNA using the complementary strand of DNA
Explain in not more than 5 sentences. If deoxyribonucleotides that lack the 3’-OH groups are added during the replication process, what do you expect will occur?
E. coli DNA polymerase V has the ability to bypass thymine dimers. However, Pol V tends to incorporate G rather than A opposite the damaged T bases. Would you expect Pol V to be more or less processive than Pol III? Explain.
2a) There are two different DNA polymerase enzymes, DNA Polymerase I and DNA Polymerase III, that are active during prokaryotic DNA replication. Suppose you generated a mutant E. coli strain in which DNA Polymerase III was inactivated (all its enzymatic activities were non-functional) - assuming that all the other enzymes involved in replication remained fully functional, how would DNA replication in these mutant cells without DNA Pol III differ from DNA replication in normal E. coli? Briefly explain why you would expect to see that change/those changes in DNA replication in the mutant cells.
A certain mutant DNA polymerase is error-prone, tending to incorporate C opposite a template A. When such a DNA polymerase replicates a segment of DNA containing an A · T base pair, what will be the DNA composition in the daughter cells after (a) one and (b) two rounds of cell division? Assume that DNA repair does not occur.
Explain how DNA polymerase and topoisomerase 2 contribute to replication in E.coli and what is the role of the role of the metal ions in the polymerase activity. B)How does the use of an RNA primer rather than a DNA primer affect the fidelity of DNA replication in E.coli?
Consider the following sequence of DNA: 3'-TTA CGG-5'What dipeptide is formed from this DNA after transcription and translation? b. If a mutation converts CGG to CGT in DNA, what dipeptide is formed? c. If a mutation converts CGG to CCG in DNA, what dipeptide is formed? d. If a mutation converts CGG to AGG in DNA, what dipeptide is formed?