Question 1

Which of the following statements best describes the directionality of DNA synthesis during replication?

Accepted Answer

DNA is synthesized in the 5' to 3' direction by DNA polymerase.

Question 2

During eukaryotic DNA replication, what is the primary function of helicase?

Accepted Answer

To catalyze the ATP-dependent unwinding of double-stranded DNA.

Question 3

Which enzyme is responsible for relieving the torsional stress generated ahead of the replication fork during DNA unwinding?

Accepted Answer

Topoisomerase

Question 4

In eukaryotic cells, which RNA polymerase is primarily responsible for transcribing protein-coding genes?

Accepted Answer

RNA polymerase II

Question 5

What is the role of the TATA box in eukaryotic transcription?

Accepted Answer

It serves as a promoter region recognized by transcription factors.

Question 6

Which of the following best explains why Okazaki fragments are formed during DNA replication?

Accepted Answer

DNA polymerase can only synthesize DNA in the 5' to 3' direction, so the lagging strand is synthesized discontinuously.

Question 7

Which of the following is a direct consequence of high levels of histone acetylation in eukaryotic chromatin?

Accepted Answer

Weakened ionic interactions between histones and DNA, promoting transcriptional activity.

Question 8

Which of the following sequences signals the addition of a poly(A) tail during eukaryotic mRNA processing?

Accepted Answer

$\mathrm{AAUAAA}$

Question 9

A mutation in the gene encoding DNA polymerase I would most directly affect which process during DNA replication?

Accepted Answer

Removal of RNA primers and replacement with DNA nucleotides

Question 10

Which of the following best describes the function of the spliceosome in eukaryotic cells?

Accepted Answer

It removes introns from pre-mRNA and joins exons together.

Question 11

Which of the following codons is recognized as the start codon in eukaryotic translation?

Accepted Answer

$\mathrm{AUG}$

Question 12

What is the correct sequence of events during the initiation of translation in bacteria?

Accepted Answer

The 50S subunit binds to the 30S initiation complex after mRNA and initiator tRNA bind the 30S subunit.

Question 13

Which of the following is true regarding the genetic code?

Accepted Answer

The stop codons UAA, UAG, and UGA do not code for any amino acid.

Question 14

Which of the following best explains the role of DNA methylation in gene regulation?

Accepted Answer

DNA methylation can lead to permanent gene inactivation and is involved in X chromosome inactivation and imprinting.

Question 15

Which of the following statements about alternative splicing is correct?

Accepted Answer

Alternative splicing allows one gene to specify multiple proteins.

Question 16

During translation, what is the function of the anticodon loop of tRNA?

Accepted Answer

It is complementary to the appropriate trinucleotide codon in the mRNA.

Question 17

Which of the following best describes the composition of the eukaryotic ribosome?

Accepted Answer

It is composed of 60S and 40S subunits.

Question 18

Which of the following is a direct result of the neutralization of lysine residues on histones by acetylation?

Accepted Answer

Weakened ionic interactions between histones and DNA, facilitating transcription.

Question 19

Which of the following best describes the function of DNA polymerase during replication?

Accepted Answer

It catalyzes the nucleophilic attack by the 3'-OH of the primer terminus upon the $\alpha$-phosphate of the incoming dNTP.

DNA Replication, Transcription, and Translation: Core Mechanisms in Molecular Biology

Study Guide - Practice Questions