Question 1

Which of the following best describes the role of the sigma (σ) factor in E. coli RNA polymerase during transcription initiation?

Accepted Answer

It recognizes and binds to specific promoter sequences, positioning RNA polymerase for accurate transcription initiation.

Question 2

A typical E. coli promoter contains two consensus sequences located at approximately which positions relative to the transcription start site?

Accepted Answer

$$-10$$ and $$-35$$

Question 3

During transcription elongation in bacteria, which of the following events occurs?

Accepted Answer

RNA polymerase moves along the template strand, synthesizing RNA in the $$5' \rightarrow 3'$$ direction.

Question 4

Which mechanism is responsible for intrinsic (rho-independent) termination of transcription in E. coli?

Accepted Answer

A GC-rich hairpin forms in the RNA followed by a series of uracils, destabilizing the RNA-DNA hybrid.

Question 5

Which eukaryotic RNA polymerase is primarily responsible for synthesizing messenger RNA (mRNA)?

Accepted Answer

RNA polymerase II

Question 6

What is the function of small nuclear ribonucleoproteins (snRNPs) in eukaryotic cells?

Accepted Answer

They are involved in the splicing of pre-mRNA by recognizing splice sites and forming the spliceosome.

Question 7

Which of the following modifications occurs at the 5’ end of a eukaryotic pre-mRNA during processing?

Accepted Answer

Addition of a methylguanosine cap

Question 8

A mutation in the gene encoding U1 snRNA would most likely affect which process?

Accepted Answer

Recognition of the 5’ splice site during pre-mRNA splicing

Question 9

Alternative splicing allows a single gene to:

Accepted Answer

Produce multiple protein isoforms by including or excluding different exons.

Question 10

Which of the following best describes the function of small nucleolar RNAs (snoRNAs)?

Accepted Answer

They are involved in the processing and modification of ribosomal RNAs (rRNAs) in the nucleolus.

Question 11

A patient with Duchenne Muscular Dystrophy has a mutation causing exon 51 to contain a stop codon. Which therapeutic strategy could restore the reading frame?

Accepted Answer

Inducing alternative splicing to skip exon 51

Question 12

Which of the following is NOT a step in the processing of eukaryotic pre-mRNA?

Accepted Answer

Addition of a Shine-Dalgarno sequence

Question 13

Which enzyme is responsible for adding the poly-A tail to eukaryotic mRNA?

Accepted Answer

Poly(A) polymerase

Question 14

In the context of mRNA degradation, which enzyme is primarily responsible for removing the poly-A tail?

Accepted Answer

Deadenylase

Question 15

Which of the following statements about tRNA processing is correct?

Accepted Answer

tRNAs undergo cleavage, base modification, and addition of CCA at the 3’ end.

Question 16

Which of the following best explains why some genetic mutations are dominant while others are recessive, in terms of mRNA and protein production?

Accepted Answer

If a single functional gene copy produces enough protein to maintain normal function, the mutation is recessive; if not, it is dominant.

Question 17

Which of the following is a direct result of RNA editing in apolipoprotein B mRNA?

Accepted Answer

A single nucleotide change creates a stop codon, resulting in a shorter protein isoform.

Question 18

Which of the following best describes the function of the 5’ cap and poly-A tail in eukaryotic mRNA?

Accepted Answer

They protect mRNA from degradation and facilitate translation.

Question 19

A researcher observes that a mutation in the 3’ splice site of a pre-mRNA leads to the inclusion of an intron in the mature mRNA. What is the most likely explanation?

Accepted Answer

The mutation prevents recognition by the spliceosome, so the intron is not removed.

Question 20

Which of the following events occurs during the processing of ribosomal RNA (rRNA) in eukaryotes?

Accepted Answer

Cleavage of a large precursor rRNA and base modifications guided by snoRNAs.

RNA Synthesis and Processing: Transcription and RNA Processing in Prokaryotes and Eukaryotes

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