Notecards-Test 1 --Bio 204.docx - The first step in rolling-circle replication is to nick circular DNA What happens next is that nucleotides are added

Notecards-Test 1 --Bio 204.docx - The first step in...

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The first step in rolling-circle replication is to nick circular DNA. What happens next is that nucleotides are added to the: a) 5’ end, which causes the 5’ end to become displaced and single-stranded. b) 3’ end, which displaces the 3’ end to become displaced and single-stranded. c) 5’ end, which causes the 3’ end to become displaced and single-stranded. d) 3’ end, which causes the 5’ end to become displaced and single-stranded. Answer: D In rolling-circle replication (right), the 5’ end becomes displaced and single-stranded. What enzyme attaches to the 3' end of the strand? a) Nothing. b) Primase. c) DNA polymerase I. d) DNA polymerase III. Answer: D 3’ 5’
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In rolling-circle replication (right), the 5’ end becomes displaced and single-stranded. What happens to this strand? a) It becomes double-stranded in a similar fashion as the lagging strand of standard DNA replication. b) It becomes double-stranded using Okazaki fragments. c) It becomes double-stranded in a similar fashion as the leading strand of standard DNA replication. d) It becomes double-stranded using reverse transcription. e) It is degraded. f) The 5’ end is elongated using DNA polymerase III. g) This strand becomes double-stranded when it finds a complementary strand displaced from a similar rolling-circle replication plasmid. Answer: A and B In rolling-circle replication (right), nicking results in two molecules, one becomes linear and the other remains circular. Both act as templates for DNA replication but the circular template does not need this enzyme to complete replication : a) Primase. b) DNA polymerase III. c) Helicase. d) Ligase . Answer: A 3’ 5’ 3’ 5’
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he figure to the right portrays a replication fork in a prokaryote with many of the molecules removed. The arrow points at a molecule at the replication fork. What is this molecule and what is it doing? a) Li g ase, which seals nicks. b) Helicase, which makes DNA single stranded. c) Gyrase, which relieves supercoiling. d) Primase, which lays down RNA primers. Answer: B The figure to the right portrays a replication fork in a prokaryote with many of the molecules removed. The arrow points at the junction of two precursor (Okazaki) fragments. What happens next here? a) Ligase seals the nick. b) DNA polymerase I adds DNA bases to the left strand and removes RNA bases on the right. c) DNA polymerase III adds DNA bases to the left strand and removes RNA bases on the right. d) Primase removes the primer and seals the nick. Answer: B The figure to the right portrays a replication fork in a prokaryote. Note that DNA polymerase III has just fallen off after doing its job. What happens next here? a) Ligase seals the nick. b) DNA polymerase I adds DNA bases to the left strand and removes RNA bases on the right.
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