Question 1

Which of the following best describes the energy source that drives the synthesis of nucleic acids during DNA replication?

Accepted Answer

Hydrolysis of phosphoanhydride bonds in dNTPs

Question 2

During DNA replication, which enzyme is responsible for unwinding the double helix, and what is the energy source for this process?

Accepted Answer

Helicase; hydrolysis of ATP

Question 3

A DNA strand is being synthesized by DNA polymerase. If 10 nucleotides are added, how many ATP equivalents are hydrolyzed in the process?

Accepted Answer

$$20$$

Question 4

Which of the following sequences is most likely to be found at an origin of replication in eukaryotic DNA?

Accepted Answer

...ATA TTA ATC TTA...

Question 5

Why is the lagging strand synthesized discontinuously during DNA replication?

Accepted Answer

DNA polymerase can only synthesize in the $$5' \rightarrow 3'$$ direction, but the lagging strand template is oriented $$3' \rightarrow 5'$$ relative to the fork movement.

Question 6

Which protein increases the processivity of DNA polymerase during replication, allowing it to add thousands of nucleotides before dissociating?

Accepted Answer

DNA clamp

Question 7

What is the function of telomerase in eukaryotic cells?

Accepted Answer

It extends the ends of linear chromosomes by adding repetitive DNA sequences, allowing room for primase and DNA polymerase to complete replication.

Question 8

Which of the following is NOT a similarity between DNA polymerase and RNA polymerase?

Accepted Answer

Template becomes part of the product

Question 9

A gene has the following coding (sense) strand: $$5'\ ATG\ CAG\ GTG\ TAA\ 3'. $$What is the mRNA sequence transcribed from this gene?

Accepted Answer

$$AUG\ CAG\ GUG\ UAA$$

Question 10

Which of the following best explains why origins of replication and promoter regions are often rich in A-T base pairs?

Accepted Answer

A-T base pairs have weaker hydrogen bonding than G-C pairs, making the DNA easier to separate.

Question 11

Which of the following steps in DNA replication uses phosphoanhydride hydrolysis for energy?

Accepted Answer

Initiation, elongation, and termination

Question 12

Which of the following is translated into protein?

Accepted Answer

Exon

Question 13

What is the role of primase during DNA replication?

Accepted Answer

It synthesizes a short RNA primer to provide a 3' OH group for DNA polymerase.

Question 14

Which of the following best describes the proofreading activity of DNA polymerase?

Accepted Answer

It removes incorrectly paired nucleotides using 3'→5' exonuclease activity.

Question 15

Which of the following is a correct statement about the directionality of nucleic acid synthesis?

Accepted Answer

Both DNA and RNA polymerases synthesize nucleic acids in the $$5' \rightarrow 3'$$ direction.

Question 16

A mutation causes the loss of 3' OH groups in all nucleotides available for DNA synthesis. What is the most likely outcome?

Accepted Answer

DNA synthesis will terminate prematurely because DNA polymerase cannot add nucleotides without a 3' OH.

Question 17

Which of the following statements about mRNA processing in eukaryotes is correct?

Accepted Answer

Exons are retained and introns are removed by splicing before translation.

Question 18

How many ATP equivalents are hydrolyzed to synthesize a 10-base RNA strand by RNA polymerase?

Accepted Answer

$$20$$

Question 19

Which of the following is a function of topoisomerase during DNA replication?

Accepted Answer

It relieves strain from overwound DNA ahead of the replication fork by hydrolyzing ATP.

Nucleic Acid Synthesis: Replication and Transcription

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