Question 1

Which experiment provided definitive evidence for the semi-conservative model of DNA replication, and what was the key result observed after two generations?

Accepted Answer

Meselson-Stahl experiment; half of the DNA was intermediate-density and half was low-density after two generations

Question 2

During DNA replication, which enzyme is responsible for relieving the twisting forces ahead of the replication fork, and what is the chemical reaction it catalyzes?

Accepted Answer

Topoisomerase; breaks and rejoins phosphodiester bonds in the DNA backbone

Question 3

In prokaryotic DNA replication, what is the function of the β subunit of DNA polymerase III holoenzyme?

Accepted Answer

It acts as the sliding DNA clamp, holding the polymerase to the DNA

Question 4

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

Accepted Answer

DNA strands are synthesized in the 5’ to 3’ direction

Question 5

What is the primary reason Okazaki fragments are formed during DNA replication?

Accepted Answer

DNA polymerase can only synthesize DNA in the 5’ to 3’ direction, so the lagging strand is synthesized discontinuously

Question 6

Which enzyme removes RNA primers and replaces them with DNA nucleotides during lagging strand synthesis in prokaryotes?

Accepted Answer

DNA polymerase I

Question 7

In eukaryotic cells, what is the role of the origin recognition complex (ORC) during DNA replication?

Accepted Answer

It marks the sites where replication will begin

Question 8

Why do eukaryotic chromosomes require telomerase for complete replication, and what is the consequence of its absence in most somatic cells?

Accepted Answer

Telomerase is needed to replicate the ends of linear chromosomes; without it, telomeres shorten and cells eventually stop dividing (senescence)

Question 9

Which of the following statements about DNA polymerases in eukaryotes is correct?

Accepted Answer

Eukaryotes have more types of DNA polymerases, with three main ones used in replication

Question 10

A student is analyzing the results of the Meselson-Stahl experiment after two generations. Which banding pattern would support the semi-conservative model of DNA replication?

Accepted Answer

One band at intermediate density and one band at low density

Question 11

Which equation best represents the addition of a nucleotide to a growing DNA strand during replication?

Accepted Answer

$$ (dNMP)_n + dNTP \rightarrow (dNMP)_{n+1} + PP_i $$

Question 12

Which protein is responsible for stabilizing single-stranded DNA during replication, preventing the strands from reannealing?

Accepted Answer

Single-strand DNA-binding proteins (SSBPs)

Question 13

In the context of bacterial DNA replication, what is a replicon?

Accepted Answer

The length of DNA replicated from one origin of replication

Question 14

Which of the following is a major difference between prokaryotic and eukaryotic DNA replication?

Accepted Answer

Eukaryotes have linear chromosomes and multiple origins of replication

Question 15

Which process is illustrated by reciprocal regions of both chromatids being labeled after DNA replication and sister chromatid exchange?

Accepted Answer

Sister chromatid exchange

Question 16

What is the function of DNA ligase during DNA replication?

Accepted Answer

It links Okazaki fragments together by forming phosphodiester bonds

Question 17

Which of the following statements about the lagging strand is correct?

Accepted Answer

It is synthesized discontinuously, resulting in Okazaki fragments

Question 18

Which enzyme is responsible for synthesizing the RNA primer required for DNA polymerase to begin synthesis?

Accepted Answer

Primase

Question 19

Which of the following best describes the predominant model of homologous recombination?

Accepted Answer

Endonuclease nicking followed by ligation and reciprocal exchange of DNA segments

DNA Replication and Recombination: Structured Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards