Question 1

Which of the following best describes the process of transcription in prokaryotes?

Accepted Answer

RNA polymerase binds directly to the promoter with the help of a sigma factor, synthesizing RNA from the DNA template.

Question 2

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

Accepted Answer

The start codon AUG codes for N-formylmethionine in Bacteria and Methionine in Archaea and Eukarya.

Question 3

A mutation changes the DNA sequence from 5'-ATG-3' to 5'-ATA-3'. What is the effect on the protein sequence?

Accepted Answer

The start codon is lost, likely preventing translation initiation.

Question 4

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

Accepted Answer

Eukaryotes use three different RNA polymerases, while prokaryotes use only one.

Question 5

Which sequence element is recognized by the sigma factor in E. coli to initiate transcription?

Accepted Answer

The -10 and -35 regions of the promoter

Question 6

What is the function of the 5' cap and poly-A tail in eukaryotic mRNA?

Accepted Answer

They protect mRNA from degradation and assist in translation initiation.

Question 7

Which of the following best describes a polycistronic mRNA?

Accepted Answer

An mRNA that encodes multiple proteins, typically found in prokaryotes.

Question 8

During translation, what is the role of the tRNA anticodon?

Accepted Answer

It base pairs with the complementary mRNA codon to ensure the correct amino acid is added.

Question 9

Which of the following is true regarding the Sec and Tat protein translocases in bacteria?

Accepted Answer

Sec exports unfolded proteins, while Tat exports folded proteins.

Question 10

A bacterial gene is regulated by a repressor that binds to the operator in the absence of an inducer. What type of regulation is this?

Accepted Answer

Negative inducible regulation

Question 11

Which of the following best explains why chaperone proteins are essential in cells?

Accepted Answer

They assist in the proper folding and refolding of proteins, preventing aggregation and misfolding.

Question 12

Which of the following is a feature of intrinsic (Rho-independent) transcription termination in bacteria?

Accepted Answer

A stem-loop structure forms in the RNA, followed by a string of uracils.

Question 13

Which of the following is true about operons in prokaryotes?

Accepted Answer

They allow multiple genes to be transcribed together under the control of a single promoter.

Question 14

Which of the following is the correct sequence of events in gene expression from DNA to protein in a eukaryotic cell?

Accepted Answer

Transcription → RNA processing → Translation

Question 15

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

Accepted Answer

Initiation of translation

Question 16

Which of the following best describes the function of the signal sequence in protein secretion?

Accepted Answer

It directs the protein to the appropriate translocase for export or membrane insertion.

Question 17

Which of the following is a consequence of the lack of introns in prokaryotic genes?

Accepted Answer

Prokaryotic mRNA does not require splicing before translation.

Question 18

Which of the following is true about the role of the ribosome in translation?

Accepted Answer

It brings together mRNA and aminoacyl tRNAs, catalyzing peptide bond formation.

Question 19

Which of the following secretion systems is unique to Gram-negative bacteria and can inject proteins directly into host cells?

Accepted Answer

Type III secretion system

Molecular Information Flow and Protein Processing in Microorganisms

Study Guide - Practice Questions