$$20 \times 20 \times 20 = 8000$$

Question 1

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

Accepted Answer

The sequence of amino acids linked by peptide bonds, read from the amino to the carboxyl terminus.

Question 2

Which of the following amino acids is NOT chiral?

Accepted Answer

Glycine

Question 3

What is the main stabilizing force in the formation of an α-helix in proteins?

Accepted Answer

Hydrogen bonds between the carbonyl oxygen of residue n and the amide hydrogen of residue n+4

Question 4

Which of the following statements about the peptide bond is CORRECT?

Accepted Answer

It links the carboxyl group of one amino acid to the amino group of the next, releasing water.

Question 5

A mutation changes a single amino acid in the primary sequence of hemoglobin. Which of the following is a possible consequence?

Accepted Answer

The mutation may alter the protein's folding, function, and possibly cause disease.

Question 6

Which of the following amino acids is most likely to disrupt an α-helix?

Accepted Answer

Proline

Question 7

How many unique tripeptides can be formed from the 20 standard amino acids?

Accepted Answer

$$20 	imes 20 	imes 20 = 8000$$

Question 8

Which of the following is a function of globular proteins?

Accepted Answer

Transporting oxygen in the blood

Question 9

Which interaction is primarily responsible for the stabilization of tertiary structure in proteins?

Accepted Answer

Hydrophobic interactions, ionic bonds, hydrogen bonds, and disulfide bridges among side chains

Question 10

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

Accepted Answer

The assembly of multiple polypeptide subunits into a functional protein complex

Question 11

Which of the following proteins is an example of a fibrous protein with a quaternary structure stabilized by disulfide bonds?

Accepted Answer

Keratin

Question 12

Which property of aromatic amino acids is particularly useful for protein quantitation by spectroscopy?

Accepted Answer

They absorb light in the ultraviolet (UV) region.

Question 13

Which of the following is a correct statement about the hydrophobic effect in protein folding?

Accepted Answer

It results from the release of water molecules from the solvation layer as the protein folds.

Question 14

Which of the following best explains why glycine is considered a 'helix breaker'?

Accepted Answer

Its small R-group (hydrogen) allows for too much conformational flexibility.

Question 15

Which of the following is a real-life example of a disease caused by a single amino acid substitution in a protein?

Accepted Answer

Sickle cell anemia

Question 16

Which of the following statements about β-sheets is TRUE?

Accepted Answer

They are stabilized by hydrogen bonds between segments of the polypeptide chain that may be distant in sequence.

Question 17

Which of the following is a function of storage proteins?

Accepted Answer

Storing amino acids for later use

Question 18

Which of the following is a correct description of collagen's quaternary structure?

Accepted Answer

A right-handed triple helix formed by three left-handed polypeptide chains rich in glycine and proline.

Question 19

Which of the following is NOT a common post-translational modification affecting protein function?

Accepted Answer

Peptide bond formation

Protein Structure and Function: Foundations of Biochemistry

Study Guide - Practice Questions