Question 1

Which statement best describes the hydrogen bonding pattern in an $\alpha$-helix?

Accepted Answer

Hydrogen bonds form between the C=O of each peptide bond and the N-H of the fourth amino acid residue away.

Question 2

What is the primary reason the peptide bond restricts rotation in the polypeptide backbone?

Accepted Answer

The peptide bond has partial double bond character, fixing atom positions in the amide plane.

Question 3

Which of the following is a key difference between fibrous and globular proteins?

Accepted Answer

Fibrous proteins are generally insoluble in water, while globular proteins are soluble.

Question 4

Collagen is an example of a fibrous protein. Which sequence pattern is characteristic of its polypeptide chains?

Accepted Answer

Every third residue is glycine in a repeating X–Pro–Gly or X–Hyp–Gly pattern.

Question 5

Which type of noncovalent interaction is most responsible for the hydrophobic core of globular proteins?

Accepted Answer

Hydrophobic interactions between nonpolar side chains

Question 6

A mutation causes a charged amino acid to be replaced by a nonpolar one in the exterior of a globular protein. What is the most likely consequence?

Accepted Answer

The protein may become less soluble and more prone to aggregation.

Question 7

Which statement about $\beta$-pleated sheets is correct?

Accepted Answer

Side chains in $\beta$-sheets alternate above and below the plane of the sheet.

Question 8

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

Accepted Answer

The spatial arrangement of multiple polypeptide chains to form multisubunit complexes.

Question 9

Which force is NOT typically involved in stabilizing the tertiary structure of proteins?

Accepted Answer

Covalent bonds between backbone atoms (excluding disulfide bridges)

Question 10

Which protein is an example of a globular protein with a compact structure and a hydrophobic core?

Accepted Answer

Hemoglobin

Question 11

What is the role of chaperone proteins in the cell?

Accepted Answer

They aid in the correct and timely folding of other proteins.

Question 12

Which of the following is true regarding the arrangement of hydrophobic and hydrophilic residues in globular proteins?

Accepted Answer

Hydrophobic residues are buried inside, while hydrophilic residues are exposed to the aqueous environment.

Question 13

A patient has a genetic disorder affecting the formation of disulfide bonds in proteins. Which protein structure level is most directly impacted?

Accepted Answer

Tertiary structure

Question 14

Which of the following statements about the collagen triple helix is correct?

Accepted Answer

It is stabilized by hydrogen bonds involving hydroxyproline and hydroxylysine.

Question 15

Which of the following is a consequence of protein misfolding in the cell?

Accepted Answer

Protein aggregation and potential cellular damage

Question 16

Which of the following best explains why genes dictate the primary structure of proteins?

Accepted Answer

Genes encode the sequence of amino acids in a polypeptide chain.

Question 17

Which of the following is NOT a property of fibrous proteins?

Accepted Answer

They have a compact, spherical shape.

Question 18

Which of the following interactions is most likely to be disrupted by a high salt concentration in the environment?

Accepted Answer

Electrostatic attractions between charged side chains

Question 19

Which statement about the folding of globular proteins is correct?

Accepted Answer

Folding occurs rapidly and spontaneously under standard biochemical conditions.

The Three-Dimensional Structure of Proteins: Organization, Folding, and Function

Study Guide - Practice Questions