Question 1

Which enzyme is responsible for unwinding the DNA double helix during DNA replication?

Accepted Answer

Helicase

Question 2

During DNA replication, which strand is synthesized discontinuously, and what are the short fragments called?

Accepted Answer

Lagging strand; Okazaki fragments

Question 3

A mutation changes a codon from UAU (tyrosine) to UAA (stop codon). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 4

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

Accepted Answer

Joins Okazaki fragments on the lagging strand

Question 5

In eukaryotic cells, which of the following modifications occurs to mRNA before it leaves the nucleus?

Accepted Answer

Addition of a 5' cap and a poly-A tail

Question 6

A bacterium acquires a gene for antibiotic resistance from a dead cell in its environment. What is this process called?

Accepted Answer

Transformation

Question 7

Which of the following is a key difference between transcription in prokaryotes and eukaryotes?

Accepted Answer

mRNA is processed (spliced, capped, polyadenylated) in eukaryotes but not in prokaryotes

Question 8

Which of the following best explains why horizontal gene transfer is important for bacterial evolution?

Accepted Answer

It enables bacteria to acquire new traits such as antibiotic resistance rapidly

Question 9

A scientist exposes bacteria to UV light, resulting in DNA damage. Which DNA repair mechanism is most likely to remove bulky lesions caused by UV?

Accepted Answer

Nucleotide excision repair

Question 10

Which of the following statements about plasmids is TRUE?

Accepted Answer

They can replicate independently of the bacterial chromosome

Question 11

A patient is infected with a bacterial strain that produces a toxin only after infection by a specific bacteriophage. What is this phenomenon called?

Accepted Answer

Lysogenic conversion

Question 12

Which of the following best describes the role of molecular chaperones in protein folding?

Accepted Answer

They help newly synthesized proteins fold correctly and prevent aggregation

Question 13

A frameshift mutation is most likely to result from which of the following?

Accepted Answer

An insertion or deletion of one or two nucleotides

Question 14

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

Accepted Answer

Relieves supercoiling and twisting stress ahead of the replication fork

Question 15

Which of the following best describes the process of transduction in bacteria?

Accepted Answer

Transfer of DNA from one bacterium to another by a bacteriophage

Question 16

Which of the following equations correctly represents the semiconservative model of DNA replication?

Accepted Answer

$$	ext{Parent DNA} ightarrow 	ext{1 Parent Strand} + 	ext{1 New Strand}$$

Question 17

Which of the following is a common function of integrons in bacteria?

Accepted Answer

Capturing and expressing multiple gene cassettes, often conferring multidrug resistance

Question 18

A bacterial cell is found to have a transposon carrying an antibiotic resistance gene. Which of the following best describes a transposon?

Accepted Answer

A DNA segment that can move from one location to another within the genome

Question 19

Which of the following best explains why DNA repair mechanisms are essential for bacterial survival?

Accepted Answer

They maintain genome stability by correcting replication errors and DNA damage

Question 20

A scientist observes that a bacterial strain can now metabolize a new sugar after acquiring a plasmid. Which process most likely enabled this adaptation?

Accepted Answer

Horizontal gene transfer via conjugation

lec 19:Bacterial Gene Transfer, DNA Replication, and Molecular Information Flow

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