Question 1

Which enzyme is responsible for relieving the supercoiling tension ahead of the replication fork in prokaryotic DNA replication?

Accepted Answer

Gyrase

Question 2

During DNA replication, which direction does DNA polymerase synthesize the new strand?

Accepted Answer

5' to 3'

Question 3

What is the primary function of DNA polymerase I in E. coli?

Accepted Answer

DNA repair, especially after UV damage

Question 4

Which of the following best describes the semiconservative model of DNA replication?

Accepted Answer

Each daughter DNA molecule consists of one parental and one new strand

Question 5

A patient’s cells show rapid telomere shortening and early cellular aging. Which enzyme is most likely deficient?

Accepted Answer

Telomerase

Question 6

Which enzyme is responsible for joining Okazaki fragments on the lagging strand during DNA replication?

Accepted Answer

Ligase

Question 7

If a mutation disables the proofreading ability of DNA polymerase, what is the most likely consequence?

Accepted Answer

Increased frequency of genetic mutations

Question 8

Which of the following statements about the backbone of DNA is correct?

Accepted Answer

It is made of alternating deoxyribose and phosphate groups

Question 9

In eukaryotic cells, DNA replication occurs during which phase of the cell cycle?

Accepted Answer

S phase of interphase

Question 10

Which of the following is NOT a function of single-strand binding proteins (SSBs) during DNA replication?

Accepted Answer

Synthesizing RNA primers

Question 11

A scientist is studying a bacterial mutant that cannot relieve positive supercoiling during DNA replication. Which enzyme is most likely defective?

Accepted Answer

Gyrase

Question 12

Which of the following best explains the 'end replication problem' in eukaryotic cells?

Accepted Answer

DNA polymerase can only synthesize in the 5' to 3' direction, leaving the ends of the lagging strand unreplicated

Question 13

Which of the following is the correct sequence of events during DNA replication?

Accepted Answer

Strand separation, primer application, DNA synthesis, primer removal, nick sealing

Question 14

Which equation best represents the number of DNA molecules after $$n$$ rounds of semiconservative replication, starting from one molecule?

Accepted Answer

$$2^n$$

Question 15

A researcher uses restriction enzymes to cut DNA at specific sites. What is the main application of this technique in molecular genetics?

Accepted Answer

To manipulate DNA for recombinant DNA technology

Question 16

Which enzyme synthesizes a short RNA primer to initiate DNA synthesis?

Accepted Answer

Primase

Question 17

Which of the following is a direct consequence of genomic instability caused by DNA replication defects?

Accepted Answer

Chromosome rearrangements and cancer

Question 18

Which DNA polymerase is the primary replication enzyme in E. coli?

Accepted Answer

DNA polymerase III

Question 19

In a DNA molecule, which base pairs with cytosine?

Accepted Answer

Guanine

Question 20

A cell is observed to have multiple origins of replication on its chromosomes. This cell is most likely:

Accepted Answer

A eukaryotic cell

DNA Replication and Molecular Genetics: Study Notes for BIO 3453

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