Question 1

Which experiment provided the first direct evidence that DNA is the genetic material responsible for heredity in bacteria?

Accepted Answer

Frederick Griffith's transformation experiment with Streptococcus pneumoniae

Question 2

In the Hershey-Chase experiment, which radioactive isotope was used to label DNA, and where was the radioactivity found after infection?

Accepted Answer

$$^{32}\mathrm{P}$$; in the bacterial pellet

Question 3

According to Chargaff’s rules, if a DNA molecule contains 30% adenine, what percentage of guanine would you expect?

Accepted Answer

20%

Question 4

Which enzyme is responsible for relieving the strain ahead of the replication fork during DNA replication?

Accepted Answer

Topoisomerase

Question 5

What is the main function of DNA ligase during DNA replication?

Accepted Answer

Joining Okazaki fragments on the lagging strand

Question 6

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

Accepted Answer

It adds nucleotides to the 3' end, synthesizing in the 5' to 3' direction

Question 7

A mutation occurs during DNA replication but is not corrected. What is the evolutionary significance of this event?

Accepted Answer

It introduces genetic variation, which can be acted upon by natural selection

Question 8

Which of the following statements about Okazaki fragments is correct?

Accepted Answer

They are short DNA segments synthesized on the lagging strand

Question 9

What is the role of single-strand binding proteins during DNA replication?

Accepted Answer

They stabilize unwound DNA strands and prevent them from re-annealing

Question 10

Which model of DNA replication was supported by the Meselson-Stahl experiment?

Accepted Answer

Semiconservative model

Question 11

A scientist isolates a DNA sample and finds that it is 18% guanine. According to Chargaff’s rules, what is the expected percentage of thymine?

Accepted Answer

32%

Question 12

Which enzyme removes RNA primers and replaces them with DNA nucleotides during replication?

Accepted Answer

DNA polymerase I

Question 13

In eukaryotic cells, DNA is packaged with proteins to form chromatin. Which proteins are primarily responsible for the first level of DNA packing?

Accepted Answer

Histones

Question 14

Which of the following best explains why DNA polymerase cannot initiate synthesis of a new strand?

Accepted Answer

It can only add nucleotides to an existing 3' end

Question 15

A patient is exposed to UV light, causing thymine dimers in their DNA. Which repair mechanism is most likely to correct this damage?

Accepted Answer

Nucleotide excision repair

Question 16

Which of the following is a correct description of the structure of a DNA double helix?

Accepted Answer

Two antiparallel strands held together by hydrogen bonds between complementary bases

Question 17

During DNA replication, which enzyme synthesizes the short RNA primer required for DNA polymerase to begin synthesis?

Accepted Answer

Primase

Question 18

Which of the following best describes the difference between dATP and ATP?

Accepted Answer

dATP contains deoxyribose, while ATP contains ribose

Question 19

Which of the following is a consequence if DNA polymerase fails to proofread during replication?

Accepted Answer

The mutation rate in the genome would increase

Question 20

In bacteria, where is the chromosome located and what is its structure?

Accepted Answer

In the nucleoid region as a supercoiled, circular DNA molecule

The Molecular Basis of Inheritance: Structure and Replication of DNA

Study Guide - Practice Questions