Question 1

Which of the following best describes the role of the ribosome's decoding center during protein translation?

Accepted Answer

It ensures the correct matching of tRNA anticodon with the mRNA codon.

Question 2

A mutation changes a codon from UAU (tyrosine) to UAA. What type of mutation is this, and what is its likely effect on the protein?

Accepted Answer

Nonsense mutation; introduces a premature stop codon.

Question 3

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

Accepted Answer

It is continuous and read in non-overlapping triplets.

Question 4

A tRNA with the anticodon 5'-GAA-3' can pair with which mRNA codon, considering wobble base pairing rules?

Accepted Answer

5'-CUU-3'

Question 5

Which post-translational modification involves the addition of a phosphate group to a protein, and what enzyme catalyzes this reaction?

Accepted Answer

Phosphorylation; kinase

Question 6

If a synthetic mRNA consisting only of repeating UUU codons is translated in vitro, which amino acid will be incorporated into the polypeptide chain?

Accepted Answer

Phenylalanine

Question 7

Which of the following best explains the effect of a frameshift mutation caused by a single nucleotide insertion?

Accepted Answer

It alters the reading frame, potentially changing all downstream amino acids.

Question 8

During translation initiation in eukaryotes, which factor binds to the mRNA's 5' cap to help recruit the ribosome?

Accepted Answer

eIF4E

Question 9

Which amino acid is specified by the start codon AUG in the genetic code?

Accepted Answer

Methionine

Question 10

A protein is found to have a disulfide bond between two cysteine residues. Which type of post-translational modification is this?

Accepted Answer

Oxidation

Question 11

Which of the following equations correctly represents the formation of a peptide bond between two amino acids?

Accepted Answer

$$HyN^*—C—C + HyN^*—C—C \rightarrow HyN^*—C—C—HyN^*—C—C + H_2O$$

Question 12

Which of the following is a consequence of the wobble hypothesis in tRNA-mRNA pairing?

Accepted Answer

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

Question 13

Which ribosomal subunit contains the peptidyl transferase center responsible for peptide bond formation?

Accepted Answer

Large subunit

Question 14

A patient has a mutation in the gene encoding a tRNA synthetase. What is the most likely effect on protein synthesis?

Accepted Answer

Incorrect amino acids may be attached to tRNAs, leading to faulty proteins.

Question 15

Which of the following codons is a stop codon in the standard genetic code?

Accepted Answer

UAG

Question 16

Which process is responsible for removing ubiquitin from a protein, reversing its targeting for degradation?

Accepted Answer

Deubiquitinase activity

Question 17

Which of the following best describes a conservative missense mutation?

Accepted Answer

A mutation that changes an amino acid to another with similar chemical properties.

Question 18

Which of the following is a real-life example of post-translational modification affecting protein function?

Accepted Answer

Phosphorylation of p53 tumor suppressor protein regulates its activity in response to DNA damage.

Question 19

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

Accepted Answer

Multiple codons can specify the same amino acid.

Protein Translation: Structure, Genetic Code, and Regulation

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