Question 1

Which experiment provided the definitive evidence that DNA, and not protein, is the genetic material in cells?

Accepted Answer

The Hershey-Chase experiment

Question 2

During the Hershey-Chase experiment, what was the significance of using radioactive phosphorus ($$^{32}P) $$and sulfur ($$^{35}S$$)?

Accepted Answer

To distinguish between viral DNA and viral protein

Question 3

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

Accepted Answer

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

Question 4

What type of bond forms between the 3' hydroxyl group of one nucleotide and the 5' phosphate group of the next nucleotide in a DNA strand?

Accepted Answer

Phosphodiester bond

Question 5

Which of the following statements about DNA replication is correct?

Accepted Answer

Each new DNA molecule consists of one parental strand and one newly synthesized strand.

Question 6

What is the role of DNA polymerase during DNA replication?

Accepted Answer

It adds nucleotides to the 3' end of a growing DNA strand.

Question 7

Why is an RNA primer necessary for DNA replication?

Accepted Answer

DNA polymerase cannot initiate synthesis without a free 3' hydroxyl group.

Question 8

Which enzyme relieves the tension created ahead of the replication fork during DNA replication?

Accepted Answer

Topoisomerase

Question 9

What is the main difference between the synthesis of the leading and lagging strands during DNA replication?

Accepted Answer

The leading strand is synthesized continuously, while the lagging strand is synthesized in short fragments.

Question 10

What is the function of DNA ligase during DNA replication?

Accepted Answer

It joins Okazaki fragments together by forming phosphodiester bonds.

Question 11

Why do linear chromosomes in eukaryotes face a problem at their ends during replication?

Accepted Answer

DNA polymerase cannot replicate the very end of the lagging strand, leading to chromosome shortening.

Question 12

How does the enzyme telomerase help maintain chromosome length in certain cells?

Accepted Answer

It extends the unreplicated ends of chromosomes using its own RNA template.

Question 13

Which of the following best describes the process of DNA proofreading?

Accepted Answer

DNA polymerase detects and corrects mismatched bases during replication.

Question 14

What type of DNA damage is caused by ultraviolet (UV) light, and how is it repaired?

Accepted Answer

UV light causes thymine dimers, which are repaired by nucleotide excision repair.

Question 15

A mutation in which enzyme would most likely result in increased sensitivity to UV light and a higher rate of skin cancer?

Accepted Answer

Nucleotide excision repair enzyme

Question 16

If a cell is unable to produce single-strand DNA-binding proteins (SSBPs), what would be the most immediate consequence during DNA replication?

Accepted Answer

Single-stranded DNA would re-anneal or form secondary structures, impeding replication.

Question 17

Which of the following equations correctly represents the condensation reaction that forms a phosphodiester bond between two nucleotides?

Accepted Answer

$$	ext{Nucleotide}_1 + 	ext{Nucleotide}_2 ightarrow 	ext{Dinucleotide} + H_2O$$

Question 18

Which of the following best explains why cells with longer initial telomeres can divide more times than cells with shorter telomeres?

Accepted Answer

Longer telomeres provide more buffer DNA, delaying the loss of essential genes during replication.

Question 19

A scientist observes that after two generations of DNA replication in $$^{14}N$$ medium, half of the DNA is of intermediate density and half is of low density. Which replication model does this observation support?

Accepted Answer

Semiconservative replication

DNA and the Gene: Synthesis and Repair

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