Question 1

Which of the following statements about bacterial genomes is correct?

Accepted Answer

Bacterial genomes typically range from 1.5 to 6 million base pairs and are usually circular.

Question 2

During DNA replication in bacteria, which enzyme is responsible for unzipping the DNA by breaking hydrogen bonds between bases?

Accepted Answer

DNA helicase

Question 3

A mutation changes a codon from $$	ext{UAC} ($$tyrosine) to $$	ext{UAA} ($$stop codon). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 4

Which of the following best describes the function of the lac operon in E. coli?

Accepted Answer

It codes for proteins that transport and catabolize lactose when lactose is available and glucose is low.

Question 5

Which of the following is TRUE regarding the directionality of DNA strands?

Accepted Answer

The 5’ end terminates at a phosphate attached to a 5’ carbon, and the 3’ end terminates with a hydroxyl group bound to a 3’ carbon.

Question 6

A bacterial cell is exposed to UV light, resulting in the formation of pyrimidine dimers. Which repair mechanism is most likely to fix this damage?

Accepted Answer

Light repair (photoreactivation)

Question 7

Which of the following statements about horizontal gene transfer is correct?

Accepted Answer

Horizontal gene transfer allows a donor cell to contribute part of its genome to a recipient cell, even of a different species.

Question 8

Which of the following best describes the role of tRNA during translation?

Accepted Answer

tRNA delivers the correct amino acids to the ribosome by matching its anticodon to the mRNA codon.

Question 9

Which of the following is a function of methylation in bacterial DNA?

Accepted Answer

Methylation adds a methyl group to adenine bases, which can regulate gene expression and protect DNA from restriction enzymes.

Question 10

A bacterium is found to require a nutrient that the wild type does not. What is this organism called?

Accepted Answer

Auxotroph

Question 11

Which of the following statements about the genetic code is correct?

Accepted Answer

There are 64 codons, of which 61 code for amino acids and 3 are stop codons.

Question 12

Which of the following is TRUE about the initiation of transcription in bacteria?

Accepted Answer

The sigma factor is necessary for RNA polymerase to recognize the promoter.

Question 13

Which of the following is a characteristic of the lagging strand during DNA replication?

Accepted Answer

It is synthesized in discontinuous segments called Okazaki fragments.

Question 14

Which of the following is a gross mutation?

Accepted Answer

Inversion

Question 15

Which of the following best describes conjugation in bacteria?

Accepted Answer

It is a unidirectional transfer of DNA from a donor to a recipient cell via a conjugation pilus.

Question 16

A bacterial cell with an integrated F plasmid is called:

Accepted Answer

Hfr cell (high frequency of recombination)

Question 17

Which of the following is TRUE about the ribosome sites during translation?

Accepted Answer

The E site is where discharged tRNAs exit the ribosome.

Question 18

Which of the following is a plausible outcome of a missense mutation?

Accepted Answer

A different amino acid is specified, which may result in a nonfunctional protein or no adverse effect.

Question 19

Which of the following statements about plasmids is correct?

Accepted Answer

Plasmids can carry genes for antibiotic resistance, virulence, and conjugation.

Question 20

Which of the following is a mechanism of self-termination during transcription in bacteria?

Accepted Answer

RNA polymerase transcribes a terminator sequence with a GC-rich region followed by an A-rich region, causing the RNA to form a hairpin and release.

Microbial Genetics: Structure, Function, and Transfer of Genetic Material

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