Question 1

Which experimental result provided the strongest evidence that DNA replication in E. coli is semiconservative?

Accepted Answer

The appearance of hybrid DNA molecules after one generation in a medium containing $$^{14}N$$

Question 2

Which enzyme is responsible for relieving the supercoiling tension ahead of the replication fork in E. coli?

Accepted Answer

DNA gyrase

Question 3

During DNA replication, which strand is synthesized discontinuously, and what are the short fragments called?

Accepted Answer

Lagging strand; Okazaki fragments

Question 4

What is the primary function of DNA polymerase I in E. coli during DNA replication?

Accepted Answer

Removing RNA primers and filling in the gaps with DNA

Question 5

Which of the following best describes the directionality of DNA synthesis by DNA polymerases?

Accepted Answer

5' to 3' direction only

Question 6

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

Accepted Answer

Accumulation of unjoined Okazaki fragments

Question 7

Which protein complex is responsible for loading the sliding DNA clamp onto the DNA template during replication?

Accepted Answer

Sliding clamp loader (γ complex)

Question 8

In eukaryotic cells, what is the function of telomerase?

Accepted Answer

Adding repetitive DNA sequences to chromosome ends

Question 9

Which of the following statements about eukaryotic DNA replication origins is correct?

Accepted Answer

Origins are recognized by the origin recognition complex (ORC)

Question 10

A temperature-sensitive mutation in a gene encoding a DNA replication protein is best described as:

Accepted Answer

A conditional mutation expressed only at restrictive temperatures

Question 11

Which of the following is NOT a function of single-stranded binding proteins (SSBPs) during DNA replication?

Accepted Answer

Synthesizing RNA primers

Question 12

Which process is essential for genetic exchange and DNA repair, involving the formation of a Holliday structure?

Accepted Answer

Homologous recombination

Question 13

What is the role of primase during DNA replication?

Accepted Answer

Synthesizing short RNA primers to provide a free 3'-OH group

Question 14

Which of the following best explains why eukaryotic chromosomes require multiple origins of replication?

Accepted Answer

Eukaryotic genomes are much larger and linear

Question 15

Which subunit of the DNA polymerase III holoenzyme is responsible for 5' to 3' polymerization?

Accepted Answer

$$\alpha$$ subunit

Question 16

A patient’s cells show progressive shortening of chromosome ends with each division. Which enzyme is most likely deficient?

Accepted Answer

Telomerase

Question 17

Which of the following steps is NOT directly involved in homologous recombination?

Accepted Answer

Phosphorylation of histones

Question 18

If a mutation impairs the proofreading function of DNA polymerase III, what is the most likely consequence?

Accepted Answer

Increased mutation rate due to uncorrected errors

Question 19

Which of the following best describes the function of the sliding DNA clamp during replication?

Accepted Answer

It increases the processivity of DNA polymerase

Question 20

Which of the following is a universal feature of DNA replication in both prokaryotes and eukaryotes?

Accepted Answer

DNA synthesis requires a primer with a free 3'-OH group

DNA Replication and Recombination: Mechanisms and Regulation

Study Guide - Practice Questions