Question 1

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 2

Which enzyme is responsible for synthesizing RNA from a DNA template during transcription in prokaryotes?

Accepted Answer

RNA polymerase

Question 3

In eukaryotes, which of the following modifications occurs to pre-mRNA before it becomes mature mRNA?

Accepted Answer

Addition of a 5’ cap and a 3’ poly-A tail

Question 4

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

Accepted Answer

The genetic code is universal and degenerate.

Question 5

A mutation causes the insertion of a single nucleotide into a coding sequence. What is the most likely consequence?

Accepted Answer

A frameshift mutation altering the reading frame

Question 6

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

Accepted Answer

Prokaryotes do not have a nuclear envelope separating transcription and translation.

Question 7

Which of the following is a function of the sigma (σ) factor in bacterial transcription?

Accepted Answer

Recognizing the promoter region to initiate transcription

Question 8

Which of the following best describes the role of aminoacyl-tRNA synthetase?

Accepted Answer

It attaches the correct amino acid to its corresponding tRNA.

Question 9

In prokaryotic translation, what is the function of the Shine-Dalgarno sequence?

Accepted Answer

It aligns the mRNA on the small ribosomal subunit for correct initiation.

Question 10

Which of the following is TRUE regarding the Sec and Tat translocase systems in bacteria?

Accepted Answer

Sec system can transport unfolded proteins, while Tat system transports folded proteins.

Question 11

A bacterial gene is regulated such that it is only expressed under heat shock conditions. Which sigma factor is most likely involved?

Accepted Answer

$$\$$sigma^{32}$$

Question 12

Which of the following post-translational modifications is important for targeting proteins to the bacterial membrane?

Accepted Answer

Addition of a signal peptide at the N-terminus

Question 13

Which secretion system in Gram-negative bacteria is known as the 'injectisome' and is used to inject effector proteins directly into host cells?

Accepted Answer

Type III secretion system (T3SS)

Question 14

Which of the following best explains why the genetic code is described as 'degenerate'?

Accepted Answer

Some amino acids are specified by more than one codon.

Question 15

During translation elongation, which site on the ribosome is responsible for holding the tRNA carrying the growing polypeptide chain?

Accepted Answer

P (peptidyl) site

Question 16

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

Accepted Answer

Eukaryotic mRNA undergoes capping, polyadenylation, and splicing.

Question 17

Which of the following best describes the energy source for peptide bond formation during translation?

Accepted Answer

The high-energy bond of the aminoacyl-tRNA

Question 18

A scientist observes that a bacterial protein is only exported to the periplasm when it contains a twin-arginine motif. Which export system is most likely responsible?

Accepted Answer

Tat system

Question 19

Which of the following is a function of chaperone proteins in bacteria?

Accepted Answer

Assisting in the proper folding of newly synthesized proteins

Question 20

Which of the following best describes a polycistronic mRNA?

Accepted Answer

An mRNA that contains multiple open reading frames, each encoding a different protein

Mechanisms of Microbial Genetics: Central Dogma, Transcription, Translation, and Protein Sorting

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