Q: Which of the following equations correctly represents the formation of a phosphodiester bond during DNA synthesis?

$$\text{(dNMP)}_{n} + \text{dNTP} \rightarrow \text{(dNMP)}_{n+1} + \text{PP}_i$$

Question 1

Which phase of the cell cycle is DNA replication most accurately associated with, and what is the primary event occurring during this phase?

Accepted Answer

S phase; DNA is synthesized and chromosomes are duplicated

Question 2

Which of the following best describes the structure of DNA as proposed by Watson and Crick?

Accepted Answer

A right-handed double helix with antiparallel strands and complementary base pairing

Question 3

What is the significance of the Meselson-Stahl experiment in the context of DNA replication?

Accepted Answer

It provided evidence for the semi-conservative model of DNA replication

Question 4

During DNA replication, which enzyme is responsible for synthesizing the RNA primer required for DNA polymerase to begin synthesis?

Accepted Answer

Primase

Question 5

Why is DNA replication described as 'semi-discontinuous' in prokaryotes such as E. coli?

Accepted Answer

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

Question 6

Which of the following statements about DNA polymerase is FALSE?

Accepted Answer

It can initiate DNA synthesis without a primer

Question 7

What is the role of single-stranded binding (SSB) proteins during DNA replication?

Accepted Answer

They keep the DNA strands separated and prevent them from re-annealing

Question 8

Which enzyme is responsible for removing RNA primers and replacing them with DNA during lagging strand synthesis in E. coli?

Accepted Answer

DNA polymerase I

Question 9

What is the function of telomerase in eukaryotic cells?

Accepted Answer

It adds repetitive DNA sequences to the ends of chromosomes to prevent loss of genetic information

Question 10

Which of the following base pairs is stabilized by three hydrogen bonds?

Accepted Answer

Guanine–Cytosine

Question 11

A mutation occurs that disables the 3' to 5' exonuclease activity of DNA polymerase. What is the most likely consequence?

Accepted Answer

The accuracy of DNA replication will decrease due to loss of proofreading

Question 12

Which of the following best explains why eukaryotic chromosomes have multiple origins of replication?

Accepted Answer

Their chromosomes are linear and much larger, requiring multiple starting points for efficient replication

Question 13

Which of the following equations correctly represents the formation of a phosphodiester bond during DNA synthesis?

Accepted Answer

$$	ext{(dNMP)}_{n} + 	ext{dNTP} ightarrow 	ext{(dNMP)}_{n+1} + 	ext{PP}_i$$

Question 14

In the Meselson-Stahl experiment, after two rounds of replication in 14N medium, what would be the expected ratio of light to hybrid DNA if DNA replication is semi-conservative?

Accepted Answer

3:1

Question 15

Which of the following is NOT a required property of genetic material?

Accepted Answer

It must be composed of proteins

Question 16

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

Accepted Answer

Topoisomerase

Question 17

If a eukaryotic cell lost the function of telomerase, what would be the most likely long-term consequence?

Accepted Answer

Chromosome ends would gradually shorten, potentially leading to loss of genetic information

Question 18

Which of the following statements about Okazaki fragments is TRUE?

Accepted Answer

They are short DNA fragments synthesized on the lagging strand

Question 19

Which of the following best describes the directionality of DNA synthesis by DNA polymerase?

Accepted Answer

It synthesizes DNA in the 5' to 3' direction

DNA Structure and Replication: Mechanisms and Experimental Evidence

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