Question 1

Which of the following best describes the coupling of transcription and translation in prokaryotes?

Accepted Answer

Translation begins before transcription is complete, allowing ribosomes to translate mRNA as it is being synthesized.

Question 2

A mutation changes the Shine–Dalgarno sequence in a bacterial mRNA from $$5'	ext{–AGGAGG–3'} to$$ $$5'	ext{–ACGCGG–3'}. $$What is the most likely effect on translation?

Accepted Answer

Translation initiation will be less efficient or may fail because ribosome binding is impaired.

Question 3

Given the following DNA coding strand: $$5'	ext{–ATG GAA CTT TGC TAA–3'}$$, what is the resulting amino acid sequence after transcription and translation?

Accepted Answer

Met – Glu – Leu – Stop

Question 4

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

Accepted Answer

Methionine and tryptophan are the only amino acids specified by a single codon.

Question 5

What is the function of the Shine–Dalgarno sequence in prokaryotic mRNA?

Accepted Answer

It positions the ribosome so that the start codon is in the P site for translation initiation.

Question 6

If the mRNA codon is $$5'	ext{–AUG–3'}$$, what is the anticodon sequence on the tRNA that pairs with it?

Accepted Answer

$$3'	ext{–UAC–5'}$$

Question 7

Which of the following best describes the role of release factors during translation termination in prokaryotes?

Accepted Answer

They add a water molecule to the growing polypeptide, releasing it from the tRNA.

Question 8

A frameshift mutation occurs in the coding region of a gene. Which of the following is the most likely consequence?

Accepted Answer

All downstream codons are altered, potentially resulting in a nonfunctional protein.

Question 9

Which ribosomal site holds the tRNA carrying the growing polypeptide chain during elongation?

Accepted Answer

P site (peptidyl)

Question 10

A bacterial gene has a strong Shine–Dalgarno sequence. What is the expected effect on translation?

Accepted Answer

Ribosomes will bind more efficiently, increasing translation initiation.

Question 11

Which of the following is TRUE regarding the degeneracy of the genetic code?

Accepted Answer

Most amino acids are specified by more than one codon.

Question 12

During translation elongation, what is the direction of ribosome movement along the mRNA?

Accepted Answer

$$5' \rightarrow 3'$$

Question 13

Which of the following best explains why a mutation in the –10 region of a bacterial promoter might reduce gene expression?

Accepted Answer

It impairs RNA polymerase binding, reducing transcription initiation.

Question 14

Which of the following is the correct sequence of events during translation initiation in prokaryotes?

Accepted Answer

Small ribosomal subunit binds Shine–Dalgarno sequence, initiator tRNA binds start codon, large subunit joins.

Question 15

A tRNA has the anticodon $$3'	ext{–UAC–5'}. $$Which mRNA codon will it recognize, and which amino acid will it carry?

Accepted Answer

Codon $$5'	ext{–AUG–3'}$$, carrying methionine

Question 16

Which of the following is a consequence of a mutation that introduces a premature stop codon into the open reading frame of a gene?

Accepted Answer

A truncated, likely nonfunctional protein will be produced.

Question 17

Which enzyme is responsible for attaching the correct amino acid to its corresponding tRNA?

Accepted Answer

Aminoacyl-tRNA synthetase

Question 18

Which of the following best describes the difference between codons and anticodons?

Accepted Answer

Codons are three-base sequences on mRNA, anticodons are complementary three-base sequences on tRNA.

Question 19

Which of the following is the correct order of tRNA movement through the ribosomal sites during elongation?

Accepted Answer

A site → P site → E site

The Genetic Code and Translation in Prokaryotes: Structure, Mechanism, and Application

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