Question 1

Which of the following statements best describes the structure of a DNA molecule?

Accepted Answer

DNA is a double-stranded helix with a backbone of deoxyribose and phosphate, and complementary nitrogenous bases paired in the center.

Question 2

Which base pairing is correct for DNA and which for RNA?

Accepted Answer

In DNA, A pairs with T and C pairs with G; in RNA, A pairs with U and C pairs with G.

Question 3

During semi-conservative DNA replication, what is the role of existing DNA strands?

Accepted Answer

Existing DNA strands serve as templates for the synthesis of new complementary strands, ensuring genetic consistency.

Question 4

Which enzyme is responsible for synthesizing RNA primers during DNA replication?

Accepted Answer

Primase

Question 5

A mutation caused by exposure to UV light is most likely to be classified as:

Accepted Answer

An induced mutation

Question 6

Which process involves the uptake of naked DNA from the environment by a bacterial cell?

Accepted Answer

Transformation

Question 7

What is the function of DNA ligase during DNA replication?

Accepted Answer

It links Okazaki fragments together on the lagging strand.

Question 8

Which of the following best describes the role of promoters in transcription?

Accepted Answer

Promoters are DNA sequences where RNA polymerase binds to start transcription.

Question 9

In the lac operon, what happens when lactose is present?

Accepted Answer

The inducer (lactose) binds to the repressor, causing it to release from the operator and allowing transcription.

Question 10

Which of the following is a key difference between generalized and specialized transduction?

Accepted Answer

Generalized transduction transfers any gene via the lytic cycle, while specialized transduction transfers specific genes via the lysogenic cycle.

Question 11

Which formula correctly represents the complementary base pairing in DNA?

Accepted Answer

$$A = T, C = G$$

Question 12

A bacterial cell is exposed to a chemical mutagen that causes deamination of cytosine. What type of mutation is this?

Accepted Answer

Induced mutation

Question 13

Which enzyme is responsible for proofreading newly synthesized DNA and correcting mismatches?

Accepted Answer

DNA polymerase

Question 14

What is the main requirement for a bacterial cell to undergo transformation?

Accepted Answer

The cell must be competent to take up DNA from its environment.

Question 15

Which process is responsible for the direct transfer of DNA from one bacterium to another via a pilus?

Accepted Answer

Conjugation

Question 16

During DNA replication, which strand is synthesized discontinuously, resulting in Okazaki fragments?

Accepted Answer

Lagging strand

Question 17

Which of the following best explains why semi-conservative replication is important for genetic stability?

Accepted Answer

It uses existing DNA strands as templates, ensuring accurate copying and reducing mutations.

Question 18

Which step in the spread of the F plasmid involves the formation of a sex pilus?

Accepted Answer

Step 2: Formation of sex pilus

Question 19

Which of the following is NOT a role of methylation of bacterial DNA in cellular processes?

Accepted Answer

Synthesis of Okazaki fragments

Question 20

A bacterium is exposed to UV light, resulting in the formation of thymine dimers. Which repair mechanism is most likely to be activated?

Accepted Answer

Photoreactivation

Microbial Genetics and DNA Processes: Study Notes

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