Question 1

Which of the following best describes the function of aminoacyl-tRNA synthetases during translation?

Accepted Answer

They attach the correct amino acid to its corresponding tRNA using ATP.

Question 2

A mutation changes the codon GAG to GTG in the β-globin gene. What is the consequence of this mutation at the protein level?

Accepted Answer

Glutamic acid is replaced by valine, which can cause sickle cell anemia.

Question 3

Which sequence is recognized by the ribosome as the start site for translation in prokaryotes?

Accepted Answer

Shine–Dalgarno sequence

Question 4

What is the main role of the Kozak sequence in eukaryotic translation?

Accepted Answer

It enhances the recognition of the start codon by the ribosome.

Question 5

Which of the following post-translational modifications is primarily responsible for targeting proteins for degradation?

Accepted Answer

Ubiquitination

Question 6

A eukaryotic mRNA is missing its 5’ cap. What is the most likely consequence?

Accepted Answer

The ribosome will not efficiently initiate translation on this mRNA.

Question 7

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

Accepted Answer

Multiple codons can encode the same amino acid.

Question 8

Which of the following is a direct result of a frameshift mutation caused by a single nucleotide insertion in an open reading frame?

Accepted Answer

All amino acids downstream of the mutation are altered, often leading to a premature stop codon.

Question 9

Which of the following statements about tRNA is FALSE?

Accepted Answer

tRNAs are never spliced or trimmed after transcription.

Question 10

Which of the following best describes the function of the signal recognition particle (SRP) during protein synthesis?

Accepted Answer

It directs ribosomes translating proteins with signal sequences to the endoplasmic reticulum.

Question 11

Which of the following is a key difference between prokaryotic and eukaryotic ribosomes?

Accepted Answer

Prokaryotic ribosomes are 70S, while eukaryotic ribosomes are 80S.

Question 12

Which of the following is NOT a typical post-translational modification?

Accepted Answer

Addition of a poly-A tail

Question 13

A protein is found to have a DNA-binding domain, a ligand-binding domain, and a dimerization domain. This protein is most likely a:

Accepted Answer

Transcription factor

Question 14

Which of the following best explains the effect of phosphorylation on protein function?

Accepted Answer

It can activate or inhibit protein activity, depending on the context.

Question 15

Which of the following is the correct equation for the formation of a peptide bond between two amino acids?

Accepted Answer

$$\mathrm{Amino\ acid}_1 + \mathrm{Amino\ acid}_2 \rightarrow \mathrm{Dipeptide} + H_2O$$

Question 16

Which of the following is a function of the poly-A tail in eukaryotic mRNA?

Accepted Answer

It enhances mRNA stability and translation efficiency.

Question 17

Which of the following best describes the role of protein domains?

Accepted Answer

They are independently folding regions of a protein that confer specific functions.

Question 18

Which of the following is a direct effect of K48-linked polyubiquitination of a protein?

Accepted Answer

The protein is targeted for degradation by the proteasome.

Question 19

A mutation in the Shine–Dalgarno sequence of a bacterial mRNA would most likely result in:

Accepted Answer

Failure of the ribosome to recognize the start codon, reducing translation initiation.

Translation, Post-Translational Modifications, and Protein Structure in Genetics

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