Question 1

Which enzyme is responsible for relieving the twisting forces that occur ahead of the replication fork during DNA replication?

Accepted Answer

Topoisomerase

Question 2

During DNA replication, which of the following statements about the synthesis of the leading and lagging strands is correct?

Accepted Answer

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

Question 3

Which of the following best describes the role of single-strand DNA-binding proteins (SSBPs) during DNA replication?

Accepted Answer

They stabilize the unwound parental DNA strands.

Question 4

A mutation prevents the formation of RNA primers during DNA replication. Which enzyme is most likely nonfunctional?

Accepted Answer

Primase

Question 5

Which of the following equations correctly represents the number of possible codons in the genetic code, given 4 RNA bases and a 3-base codon?

Accepted Answer

$$4 	imes 4 	imes 4 = 64$$

Question 6

What is the function of DNA ligase during DNA replication?

Accepted Answer

It joins Okazaki fragments by forming phosphodiester bonds.

Question 7

A patient is exposed to UV light, which causes adjacent thymine bases to form a dimer. Which DNA repair process is most likely to fix this damage?

Accepted Answer

Nucleotide excision repair

Question 8

Which of the following is true about the central dogma of molecular biology?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 9

If the DNA template strand has the sequence 3'-TACGGT-5', what is the corresponding mRNA sequence produced during transcription?

Accepted Answer

5'-AUGCCA-3'

Question 10

Which of the following best explains why the ends of linear chromosomes become shorter after each round of DNA replication?

Accepted Answer

DNA polymerase cannot add nucleotides to the 5' end of the lagging strand because there is no primer.

Question 11

Which of the following is a direct result of a mutation in the -10 box of a bacterial promoter?

Accepted Answer

Sigma factor cannot bind efficiently, reducing transcription initiation.

Question 12

Which of the following steps occurs during the processing of eukaryotic pre-mRNA?

Accepted Answer

Addition of a 5' cap and a poly(A) tail

Question 13

A scientist observes that a certain gene produces two different proteins in different tissues. Which process most likely explains this observation?

Accepted Answer

Alternative splicing of exons

Question 14

Which of the following best describes the function of tRNA during translation?

Accepted Answer

It carries amino acids to the ribosome and matches them to the mRNA codon.

Question 15

A mutation changes the codon UAU (tyrosine) to UAA. What is the most likely effect on the resulting protein?

Accepted Answer

Translation will terminate prematurely due to the introduction of a stop codon.

Question 16

Which of the following is NOT a function of RNA polymerase during transcription?

Accepted Answer

Requiring a primer to begin synthesis

Question 17

Which of the following best explains why a 3-base codon is necessary to encode all 20 amino acids?

Accepted Answer

A 3-base codon allows for $$4^3 = 64$ possible combinations, which is more than enough for 20 amino acids.

Question 18

Which of the following is a consequence of a mutation that prevents the formation of the hairpin loop during bacterial transcription termination?

Accepted Answer

Transcription will not terminate properly, resulting in longer mRNA transcripts.

Question 19

Which of the following best describes the relationship between genotype and phenotype as illustrated by the beach and forest mouse example?

Accepted Answer

Differences in DNA sequence (genotype) can lead to differences in protein structure and function, resulting in different physical traits (phenotype).

DNA Replication, Transcription, and Translation: From Genes to Proteins

Study Guide - Practice Questions