Question 1

Which experiment provided the first direct evidence that DNA, and not protein, is the genetic material responsible for transformation in bacteria?

Accepted Answer

Avery, McCarty, and MacLeod's purification of the transforming principle

Question 2

In the Hershey-Chase experiment, which radioactive isotope was used to label DNA, and what was the main finding?

Accepted Answer

$$^{32}P$$; DNA entered the bacterial cell and directed viral replication

Question 3

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

Accepted Answer

20%

Question 4

Which of the following best describes the structure of a DNA nucleotide?

Accepted Answer

A phosphate group, a deoxyribose sugar, and a nitrogenous base

Question 5

Why does pairing a purine with a pyrimidine in the DNA double helix result in a uniform width?

Accepted Answer

Because a purine (two rings) and a pyrimidine (one ring) together fit the space between the sugar-phosphate backbones

Question 6

Which enzyme is responsible for relieving the strain caused by unwinding of the DNA double helix during replication?

Accepted Answer

Topoisomerase

Question 7

During DNA replication, what is the role of primase?

Accepted Answer

It synthesizes a short RNA primer to provide a starting point for DNA polymerase

Question 8

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

Accepted Answer

Semiconservative model

Question 9

What is the main function of telomeres in eukaryotic chromosomes?

Accepted Answer

They postpone the erosion of genes near the ends of DNA molecules

Question 10

Which enzyme catalyzes the lengthening of telomeres in germ cells?

Accepted Answer

Telomerase

Question 11

In eukaryotic cells, what is the main role of histone proteins?

Accepted Answer

They package DNA into nucleosomes, aiding in chromatin structure

Question 12

Which of the following statements about DNA replication is correct?

Accepted Answer

The leading strand is synthesized continuously in the 5' to 3' direction

Question 13

What is the significance of Okazaki fragments in DNA replication?

Accepted Answer

They are short DNA segments synthesized on the lagging strand

Question 14

Which process is responsible for correcting errors that escape proofreading during DNA replication?

Accepted Answer

Mismatch repair

Question 15

A mutation causes a cell to lose the ability to produce single-strand binding proteins. What is the most likely consequence during DNA replication?

Accepted Answer

The DNA strands may re-anneal or form secondary structures, impeding replication

Question 16

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

Accepted Answer

To ensure the entire genome is replicated quickly and efficiently

Question 17

Which chemical reaction is responsible for the addition of nucleotides to a growing DNA strand?

Accepted Answer

A dehydration reaction that releases pyrophosphate ($$2P_i)$$

Question 18

If a eukaryotic cell loses the function of telomerase, what is the most likely long-term consequence?

Accepted Answer

Progressive shortening of chromosomes in germ cells, leading to loss of essential genes

Question 19

Which of the following is a real-life implication of telomere shortening in somatic cells?

Accepted Answer

It may contribute to cellular aging and limit the number of cell divisions

Question 20

Which of the following best describes euchromatin?

Accepted Answer

Loosely packed chromatin that is generally accessible for transcription

The Molecular Basis of Inheritance: DNA Structure, Function, and Replication

Study Guide - Practice Questions