Test Bank Chapter 25 BioChem by
Lehninger Latest Update 2025\2026.
1. The Meselson-Stahl experiment established that:
A) DNA polymerase has a crucial role in DNA synthesis.
B) DNA synthesis in E. coli proceeds by a conservative mechanism.
C) DNA synthesis in E. coli proceeds by a semiconservative mechanism.
D) DNA synthesis requires dATP, dCTP, dGTP, and dTTP.
E) newly synthesized DNA in E. coli has a different base composition than the preexisting DNA. -
Answer C
2. When a DNA molecule is described as replicating bidirectionally, that means that it has two:
A) chains.
B) independently replicating segment.
C) origins.
D) replication forks.
E) termination points. - Answer D
3. An Okazaki fragment is a:
A) fragment of DNA resulting from endonuclease action.
B) fragment of RNA that is a subunit of the 30S ribosome.
C) piece of DNA that is synthesized in the 3'--->5' direction.
D) segment of DNA that is an intermediate in the synthesis of the lagging strand.
E) segment of mRNA synthesized by RNA polymerase. - Answer D
4. Which one of the following statements about enzymes that interact with DNA is true?
A) E. coli DNA polymerase I is unusual in that it possesses only a 5'--->3' exonucleolytic activity.
, 5. E. coli DNA polymerase III:
A) can initiate replication without a primer.
B) is efficient at nick translation.
C) is the principal DNA polymerase in chromosomal DNA replication.
D) represents over 90% of the DNA polymerase activity in E. coli cells.
E) requires a free 5'-hydroxyl group as a primer. - Answer C
6. The proofreading function of DNA polymerase involves all of the following except:
A) a 3'--->5' exonuclease.
B) base pairing.
C) detection of mismatched base pairs.
D) phosphodiester bond hydrolysis.
E) reversal of the polymerization reaction. - Answer E
7. The 5'--->3' exonuclease activity of E. coli DNA polymerase I is involved in:
A) formation of a nick at the DNA replication origin.
B) formation of Okazaki fragments.
C) proofreading of the replication process.
D) removal of RNA primers by nick translation.
E) sealing of nicks by ligase action. - Answer D
8. Prokaryotic DNA polymerase III:
A) contains a 5'--->3' proofreading activity to improve the fidelity of replication.
B) does not require a primer molecule to initiate replication.
C) has a beta subunit that acts as a circular clamp to improve the processivity of DNA synthesis.
D) synthesizes DNA in the 3'--->5' direction.
Lehninger Latest Update 2025\2026.
1. The Meselson-Stahl experiment established that:
A) DNA polymerase has a crucial role in DNA synthesis.
B) DNA synthesis in E. coli proceeds by a conservative mechanism.
C) DNA synthesis in E. coli proceeds by a semiconservative mechanism.
D) DNA synthesis requires dATP, dCTP, dGTP, and dTTP.
E) newly synthesized DNA in E. coli has a different base composition than the preexisting DNA. -
Answer C
2. When a DNA molecule is described as replicating bidirectionally, that means that it has two:
A) chains.
B) independently replicating segment.
C) origins.
D) replication forks.
E) termination points. - Answer D
3. An Okazaki fragment is a:
A) fragment of DNA resulting from endonuclease action.
B) fragment of RNA that is a subunit of the 30S ribosome.
C) piece of DNA that is synthesized in the 3'--->5' direction.
D) segment of DNA that is an intermediate in the synthesis of the lagging strand.
E) segment of mRNA synthesized by RNA polymerase. - Answer D
4. Which one of the following statements about enzymes that interact with DNA is true?
A) E. coli DNA polymerase I is unusual in that it possesses only a 5'--->3' exonucleolytic activity.
, 5. E. coli DNA polymerase III:
A) can initiate replication without a primer.
B) is efficient at nick translation.
C) is the principal DNA polymerase in chromosomal DNA replication.
D) represents over 90% of the DNA polymerase activity in E. coli cells.
E) requires a free 5'-hydroxyl group as a primer. - Answer C
6. The proofreading function of DNA polymerase involves all of the following except:
A) a 3'--->5' exonuclease.
B) base pairing.
C) detection of mismatched base pairs.
D) phosphodiester bond hydrolysis.
E) reversal of the polymerization reaction. - Answer E
7. The 5'--->3' exonuclease activity of E. coli DNA polymerase I is involved in:
A) formation of a nick at the DNA replication origin.
B) formation of Okazaki fragments.
C) proofreading of the replication process.
D) removal of RNA primers by nick translation.
E) sealing of nicks by ligase action. - Answer D
8. Prokaryotic DNA polymerase III:
A) contains a 5'--->3' proofreading activity to improve the fidelity of replication.
B) does not require a primer molecule to initiate replication.
C) has a beta subunit that acts as a circular clamp to improve the processivity of DNA synthesis.
D) synthesizes DNA in the 3'--->5' direction.
