Q: Which of the following equations correctly represents the number of hydrogen bonds between complementary base pairs in DNA?

$$A + T = 2 \text{ hydrogen bonds}$$

Question 1

Which of the following experiments provided the definitive evidence that DNA, and not protein, is the hereditary material in bacteriophages?

Accepted Answer

Hershey and Chase's experiment using radioactive phosphorus and sulfur

Question 2

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

Accepted Answer

A five-carbon sugar, a phosphate group, and a nitrogenous base

Question 3

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

Accepted Answer

Helicase

Question 4

What is the function of the sliding clamp during DNA replication?

Accepted Answer

It increases the processivity of DNA polymerase by anchoring it to the template

Question 5

Which of the following statements about the antiparallel nature of DNA is correct?

Accepted Answer

One strand runs 5' to 3', and the other runs 3' to 5'

Question 6

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

Accepted Answer

The lagging strand is synthesized discontinuously because DNA polymerase can only add nucleotides to the 3' end

Question 7

Which of the following equations correctly represents the number of hydrogen bonds between complementary base pairs in DNA?

Accepted Answer

$$A + T = 2 	ext{ hydrogen bonds}$$

Question 8

A mutation in the gene encoding DNA ligase would most likely result in which of the following problems during DNA replication?

Accepted Answer

Failure to join Okazaki fragments on the lagging strand

Question 9

Which of the following is a key feature of semiconservative DNA replication?

Accepted Answer

Each daughter duplex contains one parental and one new strand

Question 10

In the Meselson-Stahl experiment, which result would support the dispersive model of DNA replication after two rounds of replication in $$^{14}N$$ medium?

Accepted Answer

One band at intermediate density

Question 11

Which of the following best describes the role of topoisomerase during DNA replication?

Accepted Answer

It relieves torsional stress by cutting and rejoining DNA strands

Question 12

A patient’s somatic cells show progressive telomere shortening with each cell division. Which enzyme is most likely deficient or inactive in these cells?

Accepted Answer

Telomerase

Question 13

Which of the following is NOT a requirement for a successful polymerase chain reaction (PCR)?

Accepted Answer

A supply of ribonucleotides

Question 14

During DNA replication, which activity of DNA polymerase is responsible for its proofreading function?

Accepted Answer

3' to 5' exonuclease activity

Question 15

Which of the following best explains why DNA replication is highly accurate?

Accepted Answer

Proofreading by DNA polymerase removes mismatched nucleotides

Question 16

Which of the following statements about telomerase is correct?

Accepted Answer

It uses an RNA template to extend telomeres

Question 17

A researcher is studying a eukaryotic chromosome and observes multiple replication bubbles. What does this indicate about DNA replication in eukaryotes?

Accepted Answer

Replication initiates at multiple origins simultaneously

Question 18

Which of the following best describes the function of RNA primers during DNA replication?

Accepted Answer

They provide a free 3'-OH group for DNA polymerase to begin synthesis

Question 19

Which of the following is a real-world application of the polymerase chain reaction (PCR)?

Accepted Answer

Amplifying a specific DNA segment for forensic analysis

Question 20

Which of the following best explains why the origin of replication in E. coli (oriC) is rich in A-T base pairs?

Accepted Answer

A-T base pairs form only two hydrogen bonds, making the region easier to unwind

DNA Structure and Replication: Study Notes for Genetics Students

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