Question 1

Which of the following correctly describes the structure of a DNA nucleotide?

Accepted Answer

A nitrogenous base, a pentose sugar, and a phosphate group

Question 2

During DNA replication, which enzyme is responsible for unwinding the double helix at the replication fork?

Accepted Answer

Helicase

Question 3

What is the role of single-strand binding proteins during DNA replication?

Accepted Answer

They stabilize separated DNA strands to prevent re-annealing

Question 4

Which of the following statements about DNA polymerase is TRUE?

Accepted Answer

DNA polymerase synthesizes DNA in the 5’ to 3’ direction

Question 5

Why does the lagging strand require multiple RNA primers during DNA replication?

Accepted Answer

Because synthesis is discontinuous, forming Okazaki fragments

Question 6

What is the function of DNA ligase during DNA replication?

Accepted Answer

It joins Okazaki fragments by forming phosphodiester bonds

Question 7

Which equation best represents the directionality of DNA synthesis?

Accepted Answer

$$5' \rightarrow 3'$$

Question 8

Telomerase is active in which type of cells, and what is its primary function?

Accepted Answer

Germ cells; extends telomeres to prevent chromosome shortening

Question 9

A mutation in the gene encoding DNA polymerase that eliminates its proofreading ability would most likely result in:

Accepted Answer

Higher frequency of replication errors and mutations

Question 10

Which process is responsible for correcting mismatched bases after DNA synthesis is complete?

Accepted Answer

Mismatch repair (MMR)

Question 11

A patient is exposed to excessive UV radiation, resulting in adjacent thymine bases forming abnormal bonds. Which DNA repair pathway is most likely to fix this damage?

Accepted Answer

Nucleotide excision repair

Question 12

Which of the following is a consequence of telomerase activation in somatic cells?

Accepted Answer

Cells may divide uncontrollably, contributing to cancer

Question 13

In a PCR reaction, which component is necessary for DNA polymerase to begin synthesizing new DNA?

Accepted Answer

Primers

Question 14

Which of the following best describes the function of restriction enzymes in DNA cloning?

Accepted Answer

They cut DNA at specific palindromic sequences

Question 15

During gel electrophoresis, DNA fragments migrate towards the positive electrode because:

Accepted Answer

DNA is negatively charged due to its phosphate backbone

Question 16

Which of the following is TRUE about bacterial plasmids used in biotechnology?

Accepted Answer

They are small, circular, extra-chromosomal DNA molecules

Question 17

What is the purpose of the 'marker' gene in a plasmid used for cloning?

Accepted Answer

To allow selection of bacteria that have taken up the plasmid

Question 18

Which of the following best describes gene expression?

Accepted Answer

The synthesis of a biological product encoded by a gene

Question 19

Which stage of gene expression involves converting DNA information into messenger RNA?

Accepted Answer

Transcription

Question 20

A scientist wants to amplify a specific gene from a sample of DNA. Which technique should they use?

Accepted Answer

Polymerase Chain Reaction (PCR)

DNA Structure, Replication, and Repair: Study Notes

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