Question 1

Which of the following statements best describes the difference between the sugars found in DNA and RNA?

Accepted Answer

DNA contains deoxyribose, which lacks a hydroxyl group at the 2' carbon, while RNA contains ribose, which has a hydroxyl group at the 2' carbon.

Question 2

Which nitrogenous base is found in RNA but not in DNA, and what does it replace?

Accepted Answer

Uracil (U), replaces Thymine (T)

Question 3

In the structure of DNA, what type of bond connects the nitrogenous base to the sugar, and which atoms are involved for purines?

Accepted Answer

N-glycosidic bond; N9 of purine to C1' of sugar

Question 4

Which of the following best explains why DNA is more stable than RNA under alkaline conditions?

Accepted Answer

RNA contains a 2'-hydroxyl group on ribose, which can attack the phosphodiester bond, leading to cleavage.

Question 5

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

Accepted Answer

Primase

Question 6

Which of the following base pairs is stabilized by three hydrogen bonds, and what is the biological significance of this?

Accepted Answer

Cytosine-Guanine; provides additional stability to the DNA double helix

Question 7

Which feature of the DNA double helix allows proteins to recognize specific DNA sequences without unwinding the helix?

Accepted Answer

The presence of major grooves

Question 8

A patient presents with elevated uric acid levels and symptoms of gout. Which nucleotide base metabolism is most likely involved?

Accepted Answer

Purine metabolism

Question 9

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

Accepted Answer

One strand runs 5' to 3', while the other runs 3' to 5'

Question 10

Which of the following is a correct description of semiconservative DNA replication?

Accepted Answer

Each daughter DNA molecule contains one parental strand and one newly synthesized strand.

Question 11

Which of the following is NOT a function of the major groove in DNA?

Accepted Answer

Facilitates the unwinding of DNA during replication

Question 12

Which of the following best describes the difference between prokaryotic and eukaryotic chromosomes?

Accepted Answer

Prokaryotic chromosomes are circular and found in the nucleoid; eukaryotic chromosomes are linear and found in the nucleus.

Question 13

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

Accepted Answer

Topoisomerase

Question 14

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

Accepted Answer

They stabilize single-stranded DNA and prevent it from re-annealing.

Question 15

Which of the following statements about Okazaki fragments is correct?

Accepted Answer

They are short DNA fragments synthesized discontinuously on the lagging strand.

Question 16

Which of the following is true regarding the phosphodiester bond in nucleic acids?

Accepted Answer

It links the 3' hydroxyl group of one sugar to the 5' phosphate group of the next nucleotide.

Question 17

Which of the following is a correct sequence for the flow of genetic information according to the central dogma?

Accepted Answer

DNA $$\rightarrow$$ RNA $$\rightarrow$$ Protein

Question 18

Which of the following is a clinical consequence of pyrimidine metabolism disorders?

Accepted Answer

Orotic aciduria due to defective pyrimidine synthesis

Question 19

During DNA replication, which direction does DNA polymerase synthesize the new strand?

Accepted Answer

5' to 3' direction

Nucleic Acid Structures and DNA Replication: Study Notes

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