Q: Which equation best represents the hydrolysis of nucleoside triphosphates during DNA replication?

$$\text{dNTP} \rightarrow \text{dNMP} + 2\text{P}_i$$

Question 1

Which of the following best describes the structure of DNA according to the Watson-Crick model?

Accepted Answer

DNA consists of two anti-parallel polynucleotide strands twisted into a double helix, held together by hydrogen bonds between complementary bases.

Question 2

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

Accepted Answer

Helicase

Question 3

What is the significance of the 'origin of replication' in eukaryotic cells?

Accepted Answer

It is the site where DNA strands separate and replication begins, allowing multiple replication bubbles to form for rapid copying of long DNA molecules.

Question 4

Which of the following correctly represents the base pairing rules in DNA?

Accepted Answer

A pairs with T, G pairs with C

Question 5

What is the function of DNA polymerase III during replication?

Accepted Answer

It synthesizes new DNA by adding nucleotides to the 3' end of the growing strand and proofreads each nucleotide for accuracy.

Question 6

Which equation best represents the hydrolysis of nucleoside triphosphates during DNA replication?

Accepted Answer

$$	ext{dNTP} ightarrow 	ext{dNMP} + 2	ext{P}_i$$

Question 7

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

Accepted Answer

Because the lagging strand is synthesized discontinuously in short fragments called Okazaki fragments, each requiring a primer.

Question 8

What is the role of telomeres in eukaryotic chromosomes?

Accepted Answer

They are repetitive sequences at chromosome ends that prevent loss of important DNA during replication.

Question 9

Which enzyme relieves supercoiling ahead of the replication fork by breaking, swiveling, and rejoining DNA molecules?

Accepted Answer

Topoisomerase

Question 10

In the context of DNA replication, what is the function of DNA ligase?

Accepted Answer

It connects DNA fragments by forming phosphodiester bonds, eliminating gaps in the sugar-phosphate backbone.

Question 11

Which of the following best explains why DNA replication is described as 'semi-conservative'?

Accepted Answer

Each new DNA molecule contains one old (parental) strand and one new strand.

Question 12

Which of the following is NOT a function of nucleotides in cells?

Accepted Answer

Structural proteins in the cytoskeleton

Question 13

A mutation causes DNA polymerase III to lose its proofreading ability. What is the most likely consequence?

Accepted Answer

The error rate during DNA replication will increase, leading to more mutations.

Question 14

Which of the following statements about the sugar-phosphate backbone of DNA is correct?

Accepted Answer

It is formed by phosphodiester bonds between sugars and phosphate groups.

Question 15

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

Accepted Answer

5' to 3'

Question 16

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

Accepted Answer

They stabilize the unwound parental DNA strands to prevent them from re-annealing.

Question 17

Which enzyme replaces RNA primers with DNA nucleotides during replication?

Accepted Answer

DNA polymerase I

Question 18

If a DNA molecule contains 20% adenine, what percentage of guanine would you expect according to base pairing rules?

Accepted Answer

30%

Question 19

Which of the following is a consequence of the inability to fully replicate the ends of linear chromosomes in eukaryotes?

Accepted Answer

Chromosomes get shorter with each replication, but telomeres prevent loss of essential genes.

Question 20

Which of the following best describes the process of dehydration synthesis in DNA replication?

Accepted Answer

It forms phosphodiester bonds between sugars and phosphate groups, releasing water each time a new nucleotide is added.

Lecture 16

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