Question 1

Which experimental result from the Meselson-Stahl experiment provided the strongest evidence for the semiconservative model of DNA replication?

Accepted Answer

After one generation in 14N medium, DNA extracted from E. coli showed a single intermediate density band.

Question 2

During DNA replication, which enzyme is responsible for relieving the tension created ahead of the replication fork due to unwinding?

Accepted Answer

DNA gyrase

Question 3

Which of the following best describes the role of telomerase in eukaryotic cells?

Accepted Answer

It extends the 3' end of the lagging strand template using an RNA template.

Question 4

Which of the following is a key difference between DNA replication in prokaryotes and eukaryotes?

Accepted Answer

Eukaryotes have multiple origins of replication per chromosome.

Question 5

Which enzyme is responsible for removing RNA primers and filling in the resulting gaps with DNA in E. coli?

Accepted Answer

DNA polymerase I

Question 6

What is the function of single-stranded binding proteins (SSBPs) during DNA replication?

Accepted Answer

They stabilize unwound DNA strands and prevent them from reannealing.

Question 7

A mutation in the gene encoding DNA ligase would most likely result in which of the following problems during DNA replication?

Accepted Answer

Accumulation of nicks between Okazaki fragments on the lagging strand

Question 8

Which of the following statements about Okazaki fragments is TRUE?

Accepted Answer

They are joined together by DNA ligase to form a continuous DNA strand.

Question 9

Which repair mechanism is responsible for correcting mismatched bases immediately after DNA replication?

Accepted Answer

Mismatch repair

Question 10

Which of the following best explains why DNA synthesis proceeds only in the 5' to 3' direction?

Accepted Answer

DNA polymerase can only add nucleotides to the free 3'-OH group of the growing strand.

Question 11

Which of the following equations correctly represents the base pairing in DNA?

Accepted Answer

$$A = T$$ and $$G = C$$

Question 12

A patient is diagnosed with dyskeratosis congenita, a disorder associated with short telomeres. Which cellular process is most directly affected?

Accepted Answer

Maintenance of chromosome ends during replication

Question 13

Which of the following is NOT a function of DNA polymerase III in E. coli?

Accepted Answer

Initiation of DNA synthesis

Question 14

Which of the following best describes the role of nucleosomes in eukaryotic DNA?

Accepted Answer

They serve as the basic unit of DNA packaging, consisting of DNA wrapped around histone proteins.

Question 15

Which of the following steps is unique to the lagging strand during DNA replication?

Accepted Answer

Formation of Okazaki fragments

Question 16

Which of the following is a direct consequence of the antiparallel structure of DNA?

Accepted Answer

One strand is synthesized continuously, while the other is synthesized discontinuously.

Question 17

Which of the following best describes the process of homologous recombination?

Accepted Answer

Genetic exchange at equivalent positions along two chromosomes with substantial sequence homology

Question 18

Which of the following is the correct order of events during the initiation of DNA replication in E. coli?

Accepted Answer

Unwinding by helicase, stabilization by SSBPs, primer synthesis by primase

Question 19

Which of the following equations represents the directionality of DNA synthesis?

Accepted Answer

$$5' \rightarrow 3'$$

Question 20

A mutation in the gene encoding primase would most likely result in which of the following outcomes during DNA replication?

Accepted Answer

Inability to synthesize RNA primers, preventing DNA polymerase from initiating synthesis

DNA Replication and Recombination: Structure, Mechanism, and Experimental Evidence

Study Guide - Practice Questions