Question 1

Which enzyme is responsible for unwinding the DNA double helix during DNA replication, and what is the immediate consequence of this action?

Accepted Answer

Helicase; it breaks hydrogen bonds between base pairs, creating single-stranded regions.

Question 2

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

Accepted Answer

They prevent the separated DNA strands from re-annealing.

Question 3

Which of the following best describes the semi-conservative nature of DNA replication?

Accepted Answer

Each new DNA molecule consists of one original strand and one new strand.

Question 4

What is the role of primase during DNA replication?

Accepted Answer

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

Question 5

Why is the lagging strand synthesized in short fragments during DNA replication?

Accepted Answer

Because DNA polymerase synthesizes DNA in the 5' to 3' direction, opposite to the unwinding direction on the lagging strand.

Question 6

Which enzyme is responsible for joining Okazaki fragments on the lagging strand?

Accepted Answer

Ligase

Question 7

A mutation occurs during DNA replication. Which sequence of enzyme actions is most likely to repair this mutation?

Accepted Answer

Read enzymes recognize the error, cut enzymes remove the mismatched base, replace enzymes insert the correct nucleotide.

Question 8

If a cell is exposed to high levels of radiation, what is the most likely effect on DNA replication?

Accepted Answer

The likelihood of mutations during replication will increase.

Question 9

Which of the following best explains why DNA replication is essential before cell division?

Accepted Answer

To ensure each daughter cell receives an identical set of genetic instructions.

Question 10

A scientist observes that after DNA replication, each daughter DNA molecule contains one strand with radioactive nucleotides and one without. What does this observation support?

Accepted Answer

The semi-conservative model of DNA replication.

Question 11

Which of the following is a direct result of errors not being repaired during the G2 phase after DNA replication?

Accepted Answer

The mutation may be passed on to daughter cells, contributing to genetic diversity.

Question 12

Which base pairing is correct during DNA replication?

Accepted Answer

Adenine pairs with thymine, cytosine pairs with guanine.

Question 13

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

Accepted Answer

DNA polymerase synthesizes DNA in the 5' to 3' direction.

Question 14

A pesticide exposure leads to a mutation in a cell's DNA. Which of the following is the most likely sequence of events if the mutation is not repaired?

Accepted Answer

The mutation may be passed to daughter cells during cell division.

Question 15

Which enzyme is responsible for adding new nucleotides to a growing DNA strand during replication?

Accepted Answer

DNA polymerase

Question 16

If the DNA sequence on the template strand is 5'-ATCGGTA-3', what is the sequence of the newly synthesized complementary strand?

Accepted Answer

3'-TAGCCAT-5'

Question 17

Which of the following scenarios best illustrates the importance of DNA repair enzymes?

Accepted Answer

A cell exposed to UV light develops a thymine dimer, which is recognized and corrected before cell division.

Question 18

Which of the following is NOT a function of DNA ligase during DNA replication?

Accepted Answer

Synthesizing RNA primers for DNA polymerase.

Question 19

Which phase of the cell cycle is DNA replication completed, and what happens immediately after?

Accepted Answer

S phase; the cell checks for mutations and prepares for mitosis.

Question 20

A patient is diagnosed with a genetic disorder caused by a single base substitution in a critical gene. Which process most likely failed to correct this error?

Accepted Answer

DNA repair by specialized enzymes during the G2 phase.

DNA Replication and Repair: Chapter 17 Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards