Question 1

Which of the following best explains why the double helix structure of DNA is essential for its function as genetic material?

Accepted Answer

The double helix provides a mechanism for complementary base pairing, allowing each strand to serve as a template during replication.

Question 2

Watson and Crick’s model of DNA suggested a copying mechanism based on which of the following?

Accepted Answer

The specific base pairing between adenine and thymine, and cytosine and guanine.

Question 3

During DNA replication, which bonds are broken to separate the two strands of the double helix?

Accepted Answer

Hydrogen bonds

Question 4

Which experimental result from the Meselson-Stahl experiment provided evidence against the conservative model of DNA replication?

Accepted Answer

After one round of replication, only a single intermediate-density band was observed.

Question 5

In the semiconservative model of DNA replication, what is the composition of the DNA molecules after two rounds of replication in light isotope medium?

Accepted Answer

Half the DNA molecules are hybrid, and half are light (both strands new).

Question 6

Why do eukaryotic chromosomes require multiple origins of replication, while prokaryotic chromosomes typically have only one?

Accepted Answer

Eukaryotic chromosomes are much larger and linear, so multiple origins allow timely replication.

Question 7

Which enzyme is responsible for relieving the tension created ahead of the replication fork during DNA unwinding?

Accepted Answer

Topoisomerase

Question 8

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

Accepted Answer

They prevent the separated DNA strands from re-annealing and forming hairpin structures.

Question 9

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

Accepted Answer

DNA is synthesized in the 5' to 3' direction.

Question 10

Why is an RNA primer required for DNA polymerase to begin synthesis of a new DNA strand?

Accepted Answer

DNA polymerase can only add nucleotides to an existing 3' hydroxyl group.

Question 11

Which enzyme replaces RNA primers with DNA nucleotides during lagging strand synthesis?

Accepted Answer

DNA polymerase I

Question 12

What is the function of DNA ligase during DNA replication?

Accepted Answer

It joins Okazaki fragments by forming phosphodiester bonds.

Question 13

Which of the following best explains why 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 14

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

Accepted Answer

Inability to unwind the DNA double helix, preventing replication fork progression.

Question 15

Which of the following is a direct consequence of the end replication problem in eukaryotic cells?

Accepted Answer

Shortening of chromosomes with each cell division.

Question 16

What is the primary function of telomerase in germ cells?

Accepted Answer

To extend telomeres and prevent loss of essential genetic information during replication.

Question 17

Which of the following best describes the role of nucleotide excision repair (NER) in maintaining genome integrity?

Accepted Answer

NER excises bulky, helix-distorting lesions such as pyrimidine dimers and fills the gap with new DNA.

Question 18

A patient with xeroderma pigmentosum is highly sensitive to sunlight. This is due to a defect in which cellular process?

Accepted Answer

Nucleotide excision repair of UV-induced DNA damage

Question 19

Which of the following equations correctly represents the hydrolysis of pyrophosphate ($$PP_i) $$during DNA synthesis?

Accepted Answer

$$PP_i \rightarrow 2P_i$$

Question 20

If a mutation prevented the formation of the sliding clamp during DNA replication, what would be the most likely outcome?

Accepted Answer

DNA polymerase would frequently dissociate from the template, resulting in incomplete DNA synthesis.

Bio 100 LEC Chapter 16 Module 2

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드