Q: Which equation correctly represents the addition of a nucleotide to a growing DNA strand by DNA polymerase?

$$\text{(DNA strand)} + \text{dNTP} \rightarrow \text{(DNA strand with one more nucleotide)} + 2\,\text{P}_i$$

Question 1

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

Accepted Answer

Helicase

Question 2

During DNA replication, what is the function of single-strand binding proteins?

Accepted Answer

They stabilize the unwound parental DNA strands.

Question 3

Which model of DNA replication is supported by experimental evidence and results in each daughter DNA molecule containing one old strand and one newly synthesized strand?

Accepted Answer

Semiconservative model

Question 4

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

Accepted Answer

Inability to join Okazaki fragments on the lagging strand

Question 5

Which of the following best describes the role of topoisomerase during DNA replication?

Accepted Answer

It relieves strain ahead of the replication fork by breaking, swiveling, and rejoining DNA strands.

Question 6

In the context of DNA structure, which base pairs with guanine?

Accepted Answer

Cytosine

Question 7

What is the primary function of primase during DNA replication?

Accepted Answer

It synthesizes short RNA primers using the parental DNA as a template.

Question 8

Which of the following statements about Okazaki fragments is correct?

Accepted Answer

They are short DNA fragments synthesized on the lagging strand.

Question 9

A cell exposed to ultraviolet radiation develops a thymine dimer. Which sequence of events correctly describes the nucleotide excision repair process?

Accepted Answer

Nuclease removes the damaged section, DNA polymerase fills in the gap, and DNA ligase seals the strand.

Question 10

Which equation correctly represents the addition of a nucleotide to a growing DNA strand by DNA polymerase?

Accepted Answer

$$	ext{(DNA strand)} + 	ext{dNTP} ightarrow 	ext{(DNA strand with one more nucleotide)} + 2\,	ext{P}_i$$

Question 11

Which of the following is a consequence of the inability of DNA polymerase to replace the RNA primer at the very end of the lagging strand?

Accepted Answer

The DNA molecule becomes shorter with each replication.

Question 12

Which of the following best describes euchromatin?

Accepted Answer

Less condensed chromatin that is available for transcription

Question 13

Which of the following is NOT a function of histones?

Accepted Answer

Catalyzing the elongation of new DNA strands

Question 14

Which of the following is true about telomeres?

Accepted Answer

They consist of repetitive nucleotide sequences.

Question 15

A bacteriophage infects a bacterial cell. Which of the following best describes the genetic material of the bacteriophage?

Accepted Answer

It can be either DNA or RNA.

Question 16

Which of the following statements about the sugar-phosphate backbone of DNA is correct?

Accepted Answer

It is formed by covalent bonds between the 5' phosphate and 3' hydroxyl groups of adjacent nucleotides.

Question 17

Which of the following is a real-world consequence of a mutation in a gene encoding an enzyme required for pigment synthesis, as shown in the provided materials?

Accepted Answer

The organism may lack pigment, resulting in a dramatic change in appearance.

Question 18

Which of the following best explains why the lagging strand is synthesized discontinuously?

Accepted Answer

DNA polymerase can only add nucleotides to the 3' end, so synthesis occurs in short fragments away from the replication fork.

DNA Replication and Gene Expression: Structure, Mechanisms, and Regulation

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