Question 1

Which scientist's work was critical in revealing the double helix structure of DNA through X-ray crystallography, but was not initially credited for the discovery?

Accepted Answer

Rosalind Franklin

Question 2

What is the correct pairing of nitrogenous bases in DNA, and how many hydrogen bonds are formed between each pair?

Accepted Answer

Adenine pairs with Thymine (2 bonds); Guanine pairs with Cytosine (3 bonds)

Question 3

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

Accepted Answer

DNA is synthesized in the 5' to 3' direction on both strands

Question 4

Which enzyme is responsible for unwinding the DNA double helix at the replication fork?

Accepted Answer

Helicase

Question 5

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

Accepted Answer

They prevent the separated DNA strands from re-annealing

Question 6

Why are Okazaki fragments formed during DNA replication?

Accepted Answer

Because DNA polymerase can only add nucleotides to the 3' end, and the lagging strand is synthesized discontinuously

Question 7

Which enzyme replaces RNA primers with DNA nucleotides during DNA replication?

Accepted Answer

DNA polymerase I

Question 8

What is the role of DNA ligase in DNA replication?

Accepted Answer

It joins Okazaki fragments together

Question 9

Which model of DNA replication was supported by the Meselson-Stahl experiment, and what does it state?

Accepted Answer

Semi-conservative model; each new DNA molecule consists of one parental and one new strand

Question 10

What is the main function of telomeres in eukaryotic chromosomes?

Accepted Answer

To prevent the loss of important genetic information during DNA replication

Question 11

Which enzyme helps prevent the shortening of telomeres in germ cells and some cancer cells?

Accepted Answer

Telomerase

Question 12

A mutation occurs during DNA replication but is not corrected. What is the likely consequence?

Accepted Answer

The mutation becomes a permanent change in the DNA sequence

Question 13

Which of the following best describes a nucleotide in DNA?

Accepted Answer

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

Question 14

Which of the following is a purine base found in DNA?

Accepted Answer

Adenine

Question 15

During nucleotide excision repair, which enzyme is responsible for removing the damaged DNA segment?

Accepted Answer

Nuclease

Question 16

If a DNA strand has the sequence 5'-ATCGGTA-3', what is the complementary sequence?

Accepted Answer

3'-TAGCCAT-5'

Question 17

Which of the following statements about the antiparallel nature of DNA is correct?

Accepted Answer

One strand runs 5' to 3' and the other runs 3' to 5'

Question 18

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

Accepted Answer

It requires a free 3' hydroxyl group provided by an RNA primer

Question 19

Which of the following is a real-world consequence of telomere shortening in human cells?

Accepted Answer

Cellular aging and eventual loss of cell division capacity

Question 20

Which enzyme relieves the tension created ahead of the replication fork during DNA replication?

Accepted Answer

Topoisomerase

DNA Structure and Replication: Foundations of Molecular Biology

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