$$\text{RNA synthesis: 5' \rightarrow 3'}$$

Question 1

Which of the following statements best describes the role of the sigma factor in bacterial transcription initiation?

Accepted Answer

Sigma factor recognizes and binds to the promoter region, orienting RNA polymerase for transcription initiation.

Question 2

During transcription, which strand of DNA is used as the template, and how does the resulting RNA sequence compare to the non-template strand?

Accepted Answer

The template strand is used, and the RNA sequence is complementary to the template strand but matches the non-template strand (except U for T).

Question 3

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

Accepted Answer

Eukaryotes use a poly(A) signal for termination, while bacteria use a hairpin structure.

Question 4

What is the function of the 5’ cap added to eukaryotic mRNA during processing?

Accepted Answer

It enables ribosomes to bind and protects the mRNA from degradation.

Question 5

A mutation prevents the formation of the hairpin loop in bacterial RNA. What is the most likely consequence?

Accepted Answer

Transcription will not terminate properly, resulting in longer RNA transcripts.

Question 6

Which equation correctly represents the direction of RNA synthesis by RNA polymerase?

Accepted Answer

$$	ext{RNA synthesis: 5' ightarrow 3'}$$

Question 7

Which of the following best explains why there are fewer tRNAs than codons?

Accepted Answer

Wobble pairing allows one tRNA to recognize multiple codons.

Question 8

Which of the following steps occurs during RNA splicing in eukaryotes?

Accepted Answer

snRNPs bind to exon-intron boundaries and form a spliceosome.

Question 9

Which of the following is true regarding the coupling of transcription and translation in bacteria?

Accepted Answer

Translation can begin before transcription is complete, allowing polyribosomes to form.

Question 10

What is the role of aminoacyl-tRNA synthetase in translation?

Accepted Answer

It attaches the correct amino acid to its corresponding tRNA using ATP.

Question 11

During translation, which site in the ribosome holds the tRNA carrying the growing polypeptide chain?

Accepted Answer

P site (peptidyl)

Question 12

Which of the following best describes the process of translocation during translation?

Accepted Answer

The ribosome moves one codon toward the 3’ end of the mRNA, shifting tRNAs through the E, P, and A sites.

Question 13

Which of the following is a post-translational modification that can affect protein function?

Accepted Answer

Addition of a phosphate group by an enzyme.

Question 14

A scientist observes loops in a DNA-RNA hybrid after heating viral DNA and incubating it with viral mRNA. What do these loops represent?

Accepted Answer

Regions of DNA that are not present in mature mRNA (introns).

Question 15

Which of the following equations represents the hydrolysis reaction catalyzed by the release factor during translation termination?

Accepted Answer

$$	ext{Peptidyl-tRNA} + 	ext{H}_2	ext{O} ightarrow 	ext{Polypeptide} + 	ext{tRNA}$$

Question 16

Which of the following is true about the ribosome’s catalytic activity?

Accepted Answer

Peptide bond formation is catalyzed by ribosomal RNA, making the ribosome a ribozyme.

Question 17

Which of the following best describes the fate of introns after RNA splicing?

Accepted Answer

Introns are cut out as lariats and degraded.

Question 18

Which of the following is required for the attachment of an amino acid to its tRNA?

Accepted Answer

ATP

Question 19

Which of the following best explains why mature eukaryotic mRNAs contain untranslated regions (UTRs) at both ends?

Accepted Answer

UTRs play roles in mRNA stability, localization, and translation regulation.

Transcription and Translation: Mechanisms and Regulation in Prokaryotes and Eukaryotes

Study Guide - Practice Questions