Question 1

Which experimental result from the Hershey-Chase experiment provided the strongest evidence that DNA, and not protein, is the genetic material in viruses?

Accepted Answer

Radioactive phosphorus was found inside the E. coli cells after infection.

Question 2

During DNA polymerization, a phosphodiester bond is formed between the phosphate group of the incoming nucleotide and which functional group of the last nucleotide in the growing DNA strand?

Accepted Answer

The 3' OH group

Question 3

Which of the following best describes semiconservative replication of DNA?

Accepted Answer

Each daughter DNA molecule consists of one old strand and one new strand.

Question 4

What is the role of DNA helicase during DNA replication?

Accepted Answer

It breaks hydrogen bonds between the two DNA strands to separate them.

Question 5

Which enzyme is responsible for joining Okazaki fragments during lagging strand synthesis?

Accepted Answer

DNA ligase

Question 6

A new DNA strand is always synthesized in which direction?

Accepted Answer

5' to 3'

Question 7

In the Meselson-Stahl experiment, what DNA banding pattern would you expect after one generation if DNA replication was conservative?

Accepted Answer

One heavy and one light band

Question 8

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

Accepted Answer

The two strands of DNA are antiparallel and held together by complementary base pairing.

Question 9

Which of the following best explains why DNA polymerase requires a primer to begin synthesis?

Accepted Answer

DNA polymerase can only add nucleotides to an existing 3' OH group.

Question 10

Which of the following is a function of topoisomerase during DNA replication?

Accepted Answer

It relieves tension ahead of the replication fork by cutting and rejoining DNA.

Question 11

Which of the following is true about Okazaki fragments?

Accepted Answer

They are short DNA fragments synthesized on the lagging strand.

Question 12

Which of the following best describes the role of single-strand DNA-binding proteins (SSBPs) during DNA replication?

Accepted Answer

They prevent separated DNA strands from reannealing.

Question 13

A replication bubble forms at a specific sequence called the origin of replication. Which of the following is true about replication bubbles in eukaryotic cells?

Accepted Answer

Eukaryotic cells have many replication bubbles on each chromosome.

Question 14

Which of the following is the correct sequence for the synthesis of the lagging strand during DNA replication?

Accepted Answer

Primase synthesizes RNA primers, DNA polymerase synthesizes short DNA fragments, DNA ligase joins fragments.

Question 15

Which of the following best explains why dNTPs (deoxyribonucleoside triphosphates) are used as substrates for DNA synthesis?

Accepted Answer

They have high potential energy due to their three phosphate groups, making the formation of phosphodiester bonds exergonic.

Question 16

A student is analyzing a DNA molecule and finds that 30% of the bases are adenine. According to the rules of complementary base pairing, what percentage of the bases should be thymine?

Accepted Answer

$30\%$

Question 17

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 18

At a specific area of a chromosome, the following sequence of nucleotides is present where the chain opens to form a replication fork: $3'\ \mathrm{CCTAGGCTGCAATCC}\ 5'$. An RNA primer 8 base pairs long is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence?

Accepted Answer

$5'\ \mathrm{ACGUUAGG}\ 3'$

Question 19

Which of the following best describes the function of the replisome during DNA replication?

Accepted Answer

It is a large macromolecular machine that contains all the enzymes responsible for DNA synthesis around the replication fork.

DNA and the Gene: Synthesis & Repair – Study Notes

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