Question 1

Which of the following statements best describes the directionality of eukaryotic DNA replication on a linear chromosome?

Accepted Answer

Replication is bidirectional and proceeds from several fixed origins.

Question 2

During 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

What is the chemical reaction catalyzed by DNA polymerase during chain elongation?

Accepted Answer

Nucleophilic attack by the 3'-OH of the primer terminus on the $$\alpha-$$phosphate of the incoming dNTP

Question 5

Which of the following is NOT a requirement for DNA polymerase activity?

Accepted Answer

A ribosome

Question 6

What is the role of DNA polymerase I in the removal of RNA primers during DNA replication?

Accepted Answer

It removes RNA primers and replaces them with deoxynucleotides using its exonuclease and polymerase activities.

Question 7

Which of the following best describes the synthesis of the lagging strand during DNA replication?

Accepted Answer

It is synthesized discontinuously as Okazaki fragments.

Question 8

Which of the following is a function of the TATA box in eukaryotic promoters?

Accepted Answer

It serves as the eukaryotic counterpart to the bacterial -10 region and is crucial for transcription initiation.

Question 9

What is the effect of high levels of histone acetylation on transcriptional activity?

Accepted Answer

It increases transcriptional activity by neutralizing lysine residues and weakening histone-DNA interactions.

Question 10

Which of the following statements about eukaryotic transcription termination is correct?

Accepted Answer

The pre-mRNA is cleaved 11 to 30 residues downstream of the AAUAAA signal, and a poly(A) tail is added.

Question 11

Which of the following is true regarding the capping of eukaryotic pre-mRNA?

Accepted Answer

A 7-methylguanosine cap is added to the 5' end.

Question 12

Alternative splicing of pre-mRNA allows for which of the following?

Accepted Answer

One gene to specify multiple proteins.

Question 13

During translation, what is the direction in which mRNA is read by the ribosome?

Accepted Answer

5' to 3'

Question 14

Which codon serves as the start codon in eukaryotic translation, and what amino acid does it encode?

Accepted Answer

AUG, which encodes methionine

Question 15

What is the function of aminoacyl-tRNA synthetase during translation?

Accepted Answer

It attaches the correct amino acid to its corresponding tRNA.

Question 16

Which of the following best describes the composition of the eukaryotic 80S ribosome?

Accepted Answer

It is composed of 60S and 40S subunits.

Question 17

Which site on the ribosome does the incoming aminoacyl-tRNA first bind during elongation?

Accepted Answer

A site

Question 18

What is the role of release factors during translation termination?

Accepted Answer

They recognize stop codons and promote the release of the polypeptide from the ribosome.

Question 19

DNA methylation in eukaryotes is responsible for which of the following phenomena?

Accepted Answer

X chromosome inactivation and gene imprinting

Question 20

Which enzyme is responsible for the maintenance of DNA methylation patterns during DNA replication?

Accepted Answer

DNMT1

DNA Replication, Transcription, and Translation in Eukaryotes: Core Mechanisms and Regulation

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