DNA replication machinery and repair mechanisms tested on USMLE Step 1.
About this set
39 basic cards for USMLE Step 1 Biochemistry. Set 2 of 3 in USMLE Molecular Biology. It opens with "Which enzyme unwinds the DNA double helix ahead of the replication fork?" and "Which enzyme relieves positive supercoiling generated ahead of the replication". Study it alongside the other USMLE Step 1 sets below.
39 cards · basic cards · AI-written, checked twice. Edit anything.
- Which enzyme unwinds the DNA double helix ahead of the replication fork?
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Helicase- Which enzyme relieves positive supercoiling generated ahead of the replication fork?
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Topoisomerase (DNA gyrase in bacteria)- Fluoroquinolone antibiotics inhibit which bacterial enzyme?
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DNA topoisomerase II (DNA gyrase)- What protein coats single-stranded DNA at the replication fork to prevent it from reannealing?
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Single-strand binding (SSB) protein- Which enzyme synthesizes the short RNA primer needed to begin DNA synthesis?
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Primase- DNA polymerases synthesize new DNA strands only in the ____ direction.
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5' to 3'- Which strand of DNA is synthesized continuously during replication?
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The leading strand- Which strand of DNA is synthesized discontinuously as short fragments during replication?
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The lagging strand (as Okazaki fragments)- What is the main replicative DNA polymerase in bacteria?
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DNA polymerase III- Which enzymatic activity of DNA polymerase III corrects mismatched nucleotides during synthesis?
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3' to 5' exonuclease (proofreading) activity- Which bacterial DNA polymerase removes RNA primers and fills the resulting gaps with DNA?
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DNA polymerase I- Which enzymatic activity allows DNA polymerase I to remove RNA primers ahead of it?
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5' to 3' exonuclease activity- Which enzyme seals the nick between adjacent DNA fragments by forming a phosphodiester bond?
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DNA ligase- What structure encircles DNA and holds DNA polymerase III onto the template, increasing its processivity?
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Beta sliding clamp- What is the site of active DNA unwinding and synthesis called?
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The replication fork
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