Question 1

Which of the following best describes the Central Dogma of molecular biology?

Accepted Answer

Genetic information flows from DNA to RNA to protein.

Question 2

During bacterial transcription, what is the primary function of the sigma (σ) factor in the RNA polymerase holoenzyme?

Accepted Answer

It recognizes and binds to promoter sequences to initiate transcription.

Question 3

Which sequence is recognized by the sigma factor at the -10 region of a bacterial promoter?

Accepted Answer

$$TATAAT$$

Question 4

What is the role of the Shine-Dalgarno sequence in bacterial gene expression?

Accepted Answer

It aligns the mRNA with the 16S rRNA for translation initiation.

Question 5

Which of the following statements about polycistronic mRNA is correct?

Accepted Answer

It is transcribed from a single promoter and encodes multiple related proteins.

Question 6

A mutation changes the third base of a codon from G to A, but the amino acid sequence of the protein does not change. Which concept explains this phenomenon?

Accepted Answer

Wobble hypothesis

Question 7

Which of the following is NOT a function of ribosomal RNA (rRNA) in bacteria?

Accepted Answer

Carrying amino acids to the ribosome

Question 8

What is the correct order of events during the elongation phase of bacterial translation?

Accepted Answer

Aminoacyl-tRNA enters the A site, peptide bond forms, translocation occurs

Question 9

Which of the following codons is a stop (nonsense) codon in the genetic code?

Accepted Answer

$$UAA$$

Question 10

In a bacterial cell, which molecule is responsible for catalyzing the attachment of an amino acid to its corresponding tRNA?

Accepted Answer

Aminoacyl-tRNA synthetase

Question 11

Which of the following best describes the difference between factor-independent and Rho-dependent transcription termination in bacteria?

Accepted Answer

Factor-independent termination involves a stem-loop structure in the RNA, while Rho-dependent requires the rho protein.

Question 12

A bacterial gene has the following coding sequence: 3'-TAC-5'. What will be the corresponding start codon in the mRNA after transcription?

Accepted Answer

$$AUG$$

Question 13

Which of the following statements about the bacterial RNA polymerase core enzyme is TRUE?

Accepted Answer

It consists of two alpha subunits, one beta, one beta prime, and one omega subunit.

Question 14

During translation in bacteria, which site on the ribosome does the initiator tRNA first bind?

Accepted Answer

P site

Question 15

Which of the following events requires GTP hydrolysis during bacterial translation?

Accepted Answer

Translocation of the ribosome along the mRNA

Question 16

A mutation in the Shine-Dalgarno sequence of a bacterial mRNA would most likely result in which of the following?

Accepted Answer

Impaired initiation of translation

Question 17

Which of the following is a property of the genetic code that allows multiple codons to specify the same amino acid?

Accepted Answer

Degeneracy

Question 18

In bacteria, what is the initiator tRNA charged with?

Accepted Answer

N-formylmethionine

Question 19

Which of the following best explains why transcription and translation can be coupled in bacteria but not in eukaryotes?

Accepted Answer

Bacteria lack a nuclear envelope, allowing ribosomes to access mRNA as it is being transcribed.

Question 20

Which of the following is the correct sequence of events for gene expression in bacteria?

Accepted Answer

Transcription → Translation → Protein folding

Bacterial Gene Expression: Transcription and Translation

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