1. Universal features of DNA polymerases include: A. 5\'-3\' exonuclease functio
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Question
1. Universal features of DNA polymerases include:
A. 5'-3' exonuclease function.
B. Formation of a 'closed' conformation of the polymerase when the template-nucleotide base pair is correct.
C. Use of a single magnesium ion to orient reacting molecules and assist in dissipation of the negative charge that develops during nucleotidyl transfer.
D. Alignment of conserved residues in the active site for attack of the DNA primer by the 3' OH on the incoming nucleotide.
E. Continuous unbinding and rebinding of the polymerase to the DNA template as each nucleotide is added.
2. Which of the following describes the approximate chromosomal location of the termination of replication in bacteria?
A. Termination occurs at oriC once the replication fork has advanced the entire length of the chromosome.
B. Termination occurs at a location one-quarter around the chromosome.
C. Termination occurs at a location halfway around the chromosome.
D. Termination occurs at random locations where replication forks collide.
E. Termination occurs at the first Ter site encountered by the replication fork.
41. Many of the proteins that have roles in DNA metabolism are AAA+ ATPases. Which of the following descriptions is correct in regards to what is accomplished when ATP is hydrolyzed by each of the following AAA+ ATPases:
A. In DnaA, ATP hydrolysis activates the DnaA for replication initiation.
B. In DnaC, ATP hydrolysis helps release DnaB helicase as it is loaded onto the DNA.
C. In POI Ill y and t subunits, ATP hydrolysis prevents the ß clamp from closing around the DNA.
D. In POI Ill polymerase core, ATP hydrolysis facilitates release of the polymerase from the clamp once the end of the Okazaki fragment is reached.
E. All of the above
42. Which of the following is NOT true of repairing double-strand breaks by recombination?
A. After invasion of the homologous chromosome, the 3' end of the invading strand acts as a primer for DNA synthesis.
B. The broken ends are processed, with the 3-ending strand selectively degraded to create 5' overhangs.
C. The 3' single strand extensions invade the homologous chromosome, displacing the homologous strand and base pairing with the complementary strand.
D. As a result of the two strand invasions, the two homologues are linked at two places and are called a branched intermediate.
E. The enzymes required for strand invasion belong to a class of proteins called recombinases.
Explanation / Answer
1. B. Formation of a 'closed' conformation of the polymerase when the template-nucleotide base pair is correct.
2. A. Termination occurs at oriC once the replication fork has advanced the entire length of the chromosome.
41. B. In DnaC, ATP hydrolysis helps release DnaB helicase as it is loaded onto the DNA.
42. B. The broken ends are processed, with the 3-ending strand selectively degraded to create 5' overhangs.?
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