Question 1

Which enzyme is responsible for catalyzing the nucleophilic attack by the 3'-OH group of the primer terminus on the α-phosphate of the incoming dNTP during DNA replication?

Accepted Answer

DNA polymerase

Question 2

During eukaryotic DNA replication, what is the significance of replication origins?

Accepted Answer

They are programmed to initiate replication at fixed times in S phase.

Question 3

What is the role of helicase in DNA replication?

Accepted Answer

It catalyzes the ATP-dependent unwinding of double-stranded DNA to form single-stranded DNA.

Question 4

Which enzyme relieves the torsional stress generated by helicase during DNA unwinding?

Accepted Answer

Topoisomerase

Question 5

In the removal of RNA primers during DNA replication, which enzyme is responsible for both exonuclease and polymerase activities?

Accepted Answer

DNA polymerase I

Question 6

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

Accepted Answer

It is synthesized discontinuously, forming Okazaki fragments.

Question 7

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

Accepted Answer

It serves as a promoter region for transcription initiation.

Question 8

Which transcription factor binds to the TATA box and bends DNA by 90°?

Accepted Answer

TBP (TATA box-binding protein)

Question 9

High levels of histone acetylation are associated with which of the following?

Accepted Answer

High transcriptional activity

Question 10

What is the effect of acetylation on lysine residues in histones?

Accepted Answer

It neutralizes the basic lysine residues, weakening the ionic interactions between histones and DNA.

Question 11

During posttranscriptional processing, what is added to the 5' end of eukaryotic pre-mRNA?

Accepted Answer

7-methylguanosine cap

Question 12

Which complex is responsible for splicing pre-mRNA in eukaryotes?

Accepted Answer

Spliceosome

Question 13

Alternative splicing allows one gene to:

Accepted Answer

Specify multiple proteins

Question 14

During translation, the mRNA is read in which direction?

Accepted Answer

5' to 3'

Question 15

What is the function of aminoacyl-tRNA synthetase (aaRS) in protein synthesis?

Accepted Answer

It attaches amino acids to their corresponding tRNAs.

Question 16

Which codon serves as the start codon in eukaryotic translation?

Accepted Answer

AUG

Question 17

What is the role of the anticodon loop in tRNA?

Accepted Answer

It contains a trinucleotide sequence complementary to the codon in mRNA.

Question 18

Which subunits compose the eukaryotic 80S ribosome?

Accepted Answer

60S and 40S

Question 19

During bacterial translation initiation, what is the correct sequence of events?

Accepted Answer

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

Question 20

Which equation represents the formation of a phosphodiester bond during DNA polymerization?

Accepted Answer

$$dNTP + (DNA)_{n} \rightarrow (DNA)_{n+1} + PP_i$$

DNA Replication, Transcription, and Translation in Eukaryotes

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