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 most likely to be recognized as a start site for translation in eukaryotic mRNA?

Accepted Answer

$$	ext{GCCGCCAUGG}$$

Question 4

What is the main role of the Shine–Dalgarno sequence in prokaryotic translation?

Accepted Answer

It binds to the 16S rRNA to position the ribosome at the start codon.

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 recognize the mRNA for translation initiation.

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

A mutation inserts a single nucleotide into the coding region of a gene. What is the most likely effect on the resulting protein?

Accepted Answer

A frameshift occurs, altering all downstream amino acids.

Question 9

Which of the following is NOT a function of post-transcriptional modifications in tRNA?

Accepted Answer

Initiating peptide bond formation in the ribosome

Question 10

Which of the following best describes the process of peptide bond formation during translation?

Accepted Answer

A dehydration (condensation) reaction forms a bond between the carboxyl group of one amino acid and the amino group of another.

Question 11

Which of the following is a key difference between bacterial and eukaryotic translation?

Accepted Answer

Bacterial mRNAs use a Shine–Dalgarno sequence for ribosome binding, while eukaryotic mRNAs use a 5’ cap and Kozak sequence.

Question 12

Which of the following protein modifications is most likely to regulate enzyme activity and cell signaling?

Accepted Answer

Phosphorylation

Question 13

A protein destined for secretion from a eukaryotic cell is most likely to contain which of the following features?

Accepted Answer

A signal sequence at the N-terminus recognized by the signal recognition particle (SRP)

Question 14

Which of the following best explains the molecular basis for the sickle-cell phenotype?

Accepted Answer

A hydrophobic amino acid replaces a hydrophilic one, causing hemoglobin to aggregate under low oxygen conditions.

Question 15

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

Accepted Answer

The protein is targeted for degradation by the proteasome.

Question 16

Which of the following statements about protein domains is correct?

Accepted Answer

Protein domains are sequences of 50–300 amino acids that fold into stable, functional units.

Question 17

Which of the following is a consequence of the 'wobble' position in the genetic code?

Accepted Answer

A single tRNA can recognize multiple codons for the same amino acid.

Question 18

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

Accepted Answer

They recognize stop codons and trigger the release of the polypeptide from the ribosome.

Question 19

Which of the following is a real-world example of how post-translational modifications regulate gene expression?

Accepted Answer

Ubiquitination of NIK leads to its degradation, turning off the NF-κB pathway.

Translation and Post-Translational Modifications in Genetics

Guida di studio - Domande di pratica