Question 1

Which process is responsible for synthesizing mRNA from a DNA template in bacteria?

Accepted Answer

Transcription

Question 2

What enzyme catalyzes the synthesis of mRNA from a DNA template?

Accepted Answer

RNA polymerase

Question 3

Given the DNA template strand 3'-CTCTAGAACATTTATTGGTCTTA-5', what is the corresponding mRNA sequence?

Accepted Answer

5'-GAGAUCUUGUAAUAA CCAGAAU-3'

Question 4

Using the codon table, what is the amino acid sequence produced from the mRNA 5'-GAGAUCUUGUAAUAA CCAGAAU-3'?

Accepted Answer

Glu-Ile-Leu-Stop-Pro-Glu

Question 5

A mutation changes the DNA sequence from 3'-CTCTAGAACATTTATTGGTCTTA-5' to 3'-CTCTAGAAACTATTTATTGGTCTTA-5'. What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 6

If a mutant protein is still functional in bacteria but is no longer affected by penicillin, what is the most likely change in the protein?

Accepted Answer

The protein's penicillin binding site was altered

Question 7

Which of the following best describes a difference between transcription and translation in prokaryotes and eukaryotes?

Accepted Answer

Transcription and translation are coupled in prokaryotes but separated in eukaryotes

Question 8

The mecA gene in Staphylococcus aureus, which confers methicillin resistance, is usually not transcribed due to the action of a repressor protein. What type of gene is mecA?

Accepted Answer

Inducible gene

Question 9

If the repressor protein MecI works like the LacI repressor, to which DNA region does it bind to block transcription?

Accepted Answer

Operator

Question 10

What is the name for a molecule that binds to a repressor protein, causing it to change shape and release from DNA, thus allowing gene transcription?

Accepted Answer

Inducer

Question 11

Which of the following best explains how horizontal gene transfer can contribute to antibiotic resistance in bacteria?

Accepted Answer

It enables bacteria to acquire resistance genes from other bacteria

Question 12

A bacteriophage is a virus that infects bacteria. Which of the following structures is NOT found in the simplest naked bacteriophage?

Accepted Answer

Envelope

Question 13

If a mutation in the penicillin binding protein (PBP) gene results in a stop codon early in the coding sequence, what is the most likely effect on the protein?

Accepted Answer

The protein will be truncated and likely nonfunctional

Question 14

Which of the following best describes the function of a repressor protein in gene regulation?

Accepted Answer

It blocks transcription by binding to the operator region

Question 15

Which of the following is a key difference between prokaryotic and eukaryotic gene expression?

Accepted Answer

Eukaryotes process pre-mRNA by splicing out introns

Question 16

A patient is infected with a strain of Staphylococcus aureus that is resistant to both methicillin and erythromycin. Which genetic mechanism most likely explains the acquisition of erythromycin resistance?

Accepted Answer

Transduction by a bacteriophage carrying the ermC gene

Question 17

Which of the following codons is the start codon for translation in most organisms?

Accepted Answer

$$AUG$$

Question 18

If the DNA coding strand is 5'-GAGATCTTGTAA TAACCAGAA T-3', what is the sequence of the mRNA transcribed from the template strand?

Accepted Answer

5'-GAGAUCUUGUAAUAACCAGAAU-3'

Question 19

Which of the following best describes a nonsense mutation?

Accepted Answer

A mutation that changes a codon to a stop codon

Question 20

Which of the following is a plausible reason why a mutant penicillin binding protein (PBP) still functions in the cell but is not inhibited by penicillin?

Accepted Answer

The protein's penicillin binding site has changed shape

Microbial Genetics, Antibiotic Resistance, and Gene Regulation: Study Notes

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