Question 1

Which of the following best describes the function of polyribosomes (polysomes) in protein synthesis?

Accepted Answer

They enable several ribosomes to translate a single mRNA at once, increasing efficiency.

Question 2

Which structural feature distinguishes eukaryotic translation from prokaryotic translation?

Accepted Answer

Eukaryotic mRNAs are capped at the 5′ end with 7-methylguanosine and have a poly-A tail at the 3′ end.

Question 3

The Kozak sequence in eukaryotic mRNA is important because:

Accepted Answer

It increases the efficiency of translation initiation.

Question 4

Which equation best represents the dehydration reaction forming a peptide bond between two amino acids?

Accepted Answer

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

Question 5

Which of the following is a direct consequence of protein misfolding in the brain?

Accepted Answer

Formation of abnormal protein aggregates leading to diseases such as Alzheimer's and Parkinson's.

Question 6

The 'one-gene:one-enzyme' hypothesis was revised to 'one-gene:one-polypeptide' because:

Accepted Answer

Proteins can consist of multiple polypeptide chains, and not all proteins are enzymes.

Question 7

In sickle-cell anemia, the mutation in the hemoglobin gene results in:

Accepted Answer

A single amino acid substitution in the β chain of hemoglobin.

Question 8

Which of the following best describes the primary structure of a protein?

Accepted Answer

The sequence of amino acids in the polypeptide chain.

Question 9

Which protein structure level is directly affected by a single amino acid substitution, such as in sickle-cell anemia?

Accepted Answer

Primary structure

Question 10

Which of the following statements about polypeptides and proteins is correct?

Accepted Answer

Polypeptides must fold into a three-dimensional conformation to become functional proteins.

Question 11

Which class of amino acids is most likely to be found in the interior of a globular protein?

Accepted Answer

Nonpolar, hydrophobic amino acids

Question 12

What is the role of chaperone proteins in the cell?

Accepted Answer

They mediate the folding process of polypeptides into functional proteins.

Question 13

Which of the following is a function of ubiquitins in protein quality control?

Accepted Answer

Tagging misfolded proteins for degradation by the proteasome.

Question 14

Which equation best represents the rate enhancement by enzymes in a chemical reaction?

Accepted Answer

$$\mathrm{Rate\ with\ enzyme} \gg \mathrm{Rate\ without\ enzyme}$$

Question 15

Which of the following is NOT a function of proteins in the cell?

Accepted Answer

Storing genetic information

Question 16

Which of the following best describes the quaternary structure of a protein?

Accepted Answer

The association of two or more polypeptide chains into a functional protein.

Question 17

Which protein domain is most likely to be found in a transcription factor?

Accepted Answer

DNA binding domain

Question 18

Closed-loop translation in eukaryotes provides which advantage?

Accepted Answer

Efficient ribosome recycling and protection of mRNA from degradation.

Question 19

Which of the following best explains why heterozygotes for sickle-cell anemia are largely unaffected?

Accepted Answer

They possess one normal hemoglobin allele, which compensates for the mutated allele.

Question 20

Which of the following diseases is directly linked to the presence of prions (misfolded proteins) in the brain?

Accepted Answer

Creutzfeldt–Jakob disease

Translation and Protein Structure: From Genes to Functional Proteins

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