Question 1

Which of the following best describes the semiconservative model of DNA replication?

Accepted Answer

Each daughter DNA molecule consists of one parental strand and one newly synthesized strand.

Question 2

During DNA replication, which enzyme is responsible for unwinding the double helix at the replication fork?

Accepted Answer

Helicase

Question 3

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

Accepted Answer

They stabilize unwound DNA strands and prevent them from re-annealing.

Question 4

Which enzyme relieves the strain caused by the unwinding of the DNA double helix during replication?

Accepted Answer

Topoisomerase

Question 5

Why is a primer necessary for DNA polymerase to begin synthesis of a new DNA strand?

Accepted Answer

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

Question 6

Which of the following statements about the leading and lagging strands during DNA replication is correct?

Accepted Answer

The leading strand is synthesized continuously, while the lagging strand is synthesized in short fragments.

Question 7

Okazaki fragments are joined together by which enzyme during DNA replication?

Accepted Answer

Ligase

Question 8

Which of the following best explains why DNA polymerase can only add nucleotides in the 5' to 3' direction?

Accepted Answer

The enzyme's active site only accommodates the 3' hydroxyl group of the growing strand.

Question 9

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

Accepted Answer

Inability to join Okazaki fragments on the lagging strand

Question 10

Which process is responsible for correcting errors that escape proofreading during DNA replication?

Accepted Answer

Mismatch repair

Question 11

What is the evolutionary significance of mutations that occur during DNA replication?

Accepted Answer

They are the source of genetic variation upon which natural selection acts.

Question 12

Why do eukaryotic chromosomes have multiple origins of replication?

Accepted Answer

To allow for faster and more efficient replication of large genomes.

Question 13

Which of the following best describes the role of telomeres in eukaryotic chromosomes?

Accepted Answer

They postpone the erosion of genes near the ends of DNA molecules.

Question 14

What is the function of the enzyme telomerase?

Accepted Answer

It catalyzes the lengthening of telomeres in germ cells.

Question 15

Which of the following chemical reactions occurs when a nucleotide is added to a growing DNA strand?

Accepted Answer

A dehydration reaction, releasing a molecule of pyrophosphate.

Question 16

A patient is exposed to high levels of X-rays, which cause DNA damage. Which DNA repair mechanism is most likely to be activated to remove and replace damaged DNA segments?

Accepted Answer

Nucleotide excision repair

Question 17

Which of the following equations correctly represents the directionality of DNA synthesis?

Accepted Answer

$$5' \rightarrow 3'$$

Question 18

If the sequence of a template DNA strand is $$5'	ext{-}AGCTGAC-3'$$, what is the sequence of the newly synthesized complementary strand?

Accepted Answer

$$3'	ext{-}TCGACTG-5'$$

Question 19

Which of the following best explains why prokaryotes do not experience the same end-replication problem as eukaryotes?

Accepted Answer

Prokaryotes have circular chromosomes, so they do not have ends that shorten.

The Molecular Basis of Inheritance (Campbell Biology, Ch. 16) – Study Notes

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