Choose the best answer.
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1 | | Which of the three models of DNA replication proposed that the original double helix remained entirely intact throughout the process? |
| | A) | Conservative model. |
| | B) | Semiconservative model. |
| | C) | Dispersive model. |
| | D) | Destructive model. |
| | E) | None of these. |
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2 | | Which statement about bacterial DNA replication is correct? |
| | A) | DNA replication begins at several places along the chromosome. |
| | B) | DNA replication begins at the origin and travels in both directions. |
| | C) | DNA replication begins at the origin and travels around the chromosome back to the origin. |
| | D) | DNA replication begins at a GC rich region of the chromosome. |
| | E) | All of these are correct. |
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3 | | Why is an AT rich region part of the E. coli oriC? |
| | A) | DnaA proteins bind to AT rich sites. |
| | B) | DnaC proteins bind to AT rich sites. |
| | C) | AT base pairs are more easily separated than GC base pairs. |
| | D) | AT base pairs contain more hydrogen bonds than GC base pairs. |
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4 | | Which enzyme produces the first piece of nucleic acid synthesized in E. coli DNA replication? |
| | A) | DNA primase |
| | B) | DNA polymerase (polIII) |
| | C) | DNA polymerase (polI) |
| | D) | DNA ligase |
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5 | | What is a key difference between DNA polIII and DNA ligase? |
| | A) | Only DNA polIII synthesizes phosphoester bonds. |
| | B) | Only DNA ligase synthesizes phosphoester bonds. |
| | C) | DNA polIII can synthesize DNA from 3'-5'. |
| | D) | DNA ligase can use energy from ATP rather than nucleotides. |
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6 | | What is the major difference between the lagging and leading strands? |
| | A) | On the leading strand, DNA synthesis occurs from 5' to 3', while DNA synthesis occurs from 3' to 5' on the lagging strand. |
| | B) | DNA polymerase is able to continuously add new nucleotides on the leading strand while it must keep 'starting over' on the lagging strand. |
| | C) | The lagging strand requires only a single primer while the leading strand requires many. |
| | D) | Helicase opens the leading strand at a faster rate than the lagging strand. |
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7 | | What explanation for Okazaki fragments is the most accurate? |
| | A) | DNA polymerase is only able to synthesize 1000-2000 bonds before it falls off the strand. |
| | B) | DNA polymerase must stop to check its work every 1000-2000 nucleotides. |
| | C) | DNA polymerase requires a free 3' OH group to attach new nucleotides; primers are produced on the lagging strand every 1000-2000 nucleotides. |
| | D) | All of these are accurate statements. |
| | E) | None of these are accurate statements. |
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8 | | What DNA sequence is required for termination of replication in E. coli? |
| | A) | oriC |
| | B) | ter |
| | C) | Tus |
| | D) | Fork |
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9 | | What is the major difference between T1 and T2 ter sequences? |
| | A) | Tus binds to T1 but not T2. |
| | B) | Tus binds to T2 but not T1. |
| | C) | T1 stops only counterclockwise-moving forks while T2 stops only clockwise-moving forks. |
| | D) | T2 stops only counterclockwise-moving forks while T1 stops only clockwise-moving forks. |
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10 | | What enzyme performs decatenation? |
| | A) | Polymerase. |
| | B) | Topoisomerase. |
| | C) | Telomerase. |
| | D) | Decatenase. |
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11 | | Which is a correct description of the replisome? |
| | A) | The replisome is a complex of several proteins. |
| | B) | The replisome includes DNA polymerase, DNA helicase, and primase. |
| | C) | The replisome can be found at the replication fork during DNA synthesis. |
| | D) | All of these are correct descriptions. |
| | E) | None of the above are correct. |
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12 | | Which of the following is a description of the proofreading function of DNA polymerase? |
| | A) | Endonuclease cleavage. |
| | B) | Exonuclease cleavage. |
| | C) | Methylation. |
| | D) | An induced-fit phenomenon. |
| | E) | All of these. |
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13 | | Which of the following is not a mechanism by which E. coli can coordinate DNA replication with cell division? |
| | A) | DnaA protein does not efficiently bind to hemimethylated binding sites in the oriC. |
| | B) | DNA polymerase does not efficiently bind to mismatched base pairs. |
| | C) | DnaA protein is rapidly degraded after the initiation of DNA replication. |
| | D) | DnaA proteins must bind to a minimum number of binding sites in the oriC. |
| | E) | None of these; all are such mechanisms. |
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14 | | Which of the following is a key difference between eukaryotic and prokaryotic DNA replication? |
| | A) | Eukaryotic origins of replication contain a high % of AT base pairs and require protein binding for correct function. |
| | B) | In eukaryotes, DNA replication proceeds bidirectionally from the origin of replication. |
| | C) | Eukaryotes contain several different DNA polymerases. |
| | D) | Telomerase is required to replicate the ends of eukaryotic chromosomes. |
| | E) | None of these: They could all also describe prokaryotic DNA replication. |
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15 | | What aspect of DNA polymerase function necessitates use of telomerase in eukaryotes? |
| | A) | 3'-5' exonuclease function. |
| | B) | 5'-3' processivity. |
| | C) | Induced fit impact on incorporation of only correct bases. |
| | D) | All of these. |
| | E) | None of these. |
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16 | | Telomerase activity in humans is generally restricted to the germ line, cancerous cells, and a few specific adult cell types. How would this be expected to impact humans? |
| | A) | Cancer cells can divide indefinitely. |
| | B) | Because there is a difference in number of divisions, sperm would be expected to have shorter telomeres than oocytes. |
| | C) | Rapidly dividing populations of cells have telomeres equal in size to slowly dividing populations of cells. |
| | D) | All of these. |
| | E) | None of these. |
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17 | | Base pairing rules are critical for the ability of each DNA strand to act as a template. |
| | A) | True |
| | B) | False |
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18 | | Meselson and Stahl's experiment was able to demonstrate in one round of division that DNA replication is a semiconservative process. |
| | A) | True |
| | B) | False |
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19 | | DNA replication requires an origin, where the two strands can be separated. |
| | A) | True |
| | B) | False |
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20 | | DnaA protein is unable to bind hemimethylated DNA because its binding site includes a GATC methylation site. |
| | A) | True |
| | B) | False |
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21 | | DNA replication proceeds only in one direction. |
| | A) | True |
| | B) | False |
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22 | | DNA polymerase recognizes correct base pairs and incorporates new nucleotides which are correctly base paired to the template. |
| | A) | True |
| | B) | False |
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23 | | The fidelity of DNA replication in E. coli is about one mistake per 100 million incorporated nucleotides. |
| | A) | True |
| | B) | False |
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24 | | Fig 11.7 is an accurate depiction of the relative position of the enzymes required for DNA replication. |
| | A) | True |
| | B) | False |
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25 | | DNA polymerase moves toward the replication fork on both the lagging and leading strands. |
| | A) | True |
| | B) | False |
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26 | | DNA polymerase uses energy contained in the linkage between phosphate groups to drive DNA synthesis. |
| | A) | True |
| | B) | False |
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27 | | After DNA replication, the newly synthesized strand contains only newly synthesized histones. |
| | A) | True |
| | B) | False |
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