9) In E. coli, which enzyme catalyzes the elongation of a new DNA strand in the
ID: 3164612 • Letter: 9
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9) In E. coli, which enzyme catalyzes the elongation of a new DNA strand in the 5- 3' direction? A) primase B) DNA ligase C)DNA polymerase III D) helicase 10) How does the enzyme telomerase meet the challenge of replicating the ends of linear chromosomes? A) It adds a single 5' cap structure that resists degradation by nucleases. B) It causes specific double-strand DNA breaks that result in blunt ends on both strands. C) It catalyzes the lengthening of telomeres, compensating for the shortening that could occur during replication without telomerase activity D) It adds numerous GC pairs, which resist hydrolysis and maintain chromosome integrity 11) In E. coli, what is the function of DNA polymerase II1? A) to unwind the DNA helix during replication B) to seal together the broken ends of DNA strands C) to add nucleotides to the 3' end of a growing DNA strand D) to degrade damaged DNA molecules 12) Which of the following statements correctly describes the difference between the leading and the lagging strands of DNA during DNA replication? A) The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction. B) The leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end. C) The lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together D) The leading strand is synthesized at twice the rate of the lagging strand. 13) What is the function of the enzyme topoisomerase in DNA replication? A) relieving strain in the DNA ahead of the replication fork caused by the untwisting of the double helix B) elongating new DNA at a replication fork by adding nucleotides to the existing chain C) reattaching the hydrogen bonds between the base pairs in the double helix D) building RNA primers using the parental DNA strand as a template 14) Which of the following types of molecules help to hold the DNA strands apart while they are being replicated? A) primase B) ligase C) DNA polymerase D) single-strand DNA binding proteins 15) Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight, and mutations to the DNA in their skin cells are left uncorrected. Why are the mutations not corrected in individuals with this disorder? A) The disorder makes cells unable to replicate DNA. B) The disorder causes mitosis to stop during metaphase. C) The disorder makes cells unable to form chromosomes. D) The disorder causes cells to be unable to repair thymine dimers.Explanation / Answer
9. DNA Polymerase III
10. it add numerous GC pairs, which resist hydrolysis and maintain chromosome integrity
11. To add the nucleotides to the 3’ end of the growing DNA strand
12. The leading strand is synthesized in the same direction as movement of the replication fork and the lagging strands of DNA is synthesized in the opposite direction
13. relieving strain in the DNA ahead of the replication fork caused by the untwisting of the double helix
14. Single stranded DNA binding protein
15 the disorder causes cells to be unable to repair thymine dimers
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