Q: Which equation correctly represents the fraction of protein bound to ligand ($$\theta) in a $$simple binding equilibrium?

$$\theta = \dfrac{[PL]}{[PL] + [P]}$$

Question 1

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

Accepted Answer

The sequence of amino acids in a polypeptide chain, read from the N-terminal to the C-terminal.

Question 2

A single amino acid substitution in hemoglobin can result in sickle-cell anemia. This is an example of how:

Accepted Answer

Changes in primary structure can affect protein function.

Question 3

Which bond in the protein backbone is unable to rotate due to its partial double-bond character?

Accepted Answer

Peptide bond between the carbonyl carbon and the amino nitrogen.

Question 4

Which of the following amino acids is most likely to disrupt an α-helix due to its cyclic structure and lack of N-H for hydrogen bonding?

Accepted Answer

Proline

Question 5

In a typical α-helix, how many amino acids are there per turn and what is the rise per turn?

Accepted Answer

$$3.6$$ amino acids per turn and $$5.4\AA$$ rise per turn.

Question 6

Which of the following interactions is NOT typically involved in stabilizing the tertiary structure of a protein?

Accepted Answer

Peptide bond formation between amino acids

Question 7

Collagen is a fibrous protein with a unique triple helix structure. Which amino acid is found at every third position in its sequence?

Accepted Answer

Glycine

Question 8

Which of the following statements about protein folding is TRUE?

Accepted Answer

Protein folding is a spontaneous process driven by the hydrophobic effect.

Question 9

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

Accepted Answer

The arrangement of multiple polypeptide subunits with respect to each other.

Question 10

Which of the following is a consequence of protein denaturation?

Accepted Answer

Loss of biological activity due to disruption of 2°, 3°, or 4° structure.

Question 11

Which equation correctly represents the fraction of protein bound to ligand ($$	heta) in a $$simple binding equilibrium?

Accepted Answer

$$	heta = \dfrac{[PL]}{[PL] + [P]}$$

Question 12

The Hill coefficient ($$n) in $$ligand binding describes:

Accepted Answer

The degree of cooperativity between binding sites.

Question 13

Which of the following best explains positive cooperativity in hemoglobin's oxygen binding?

Accepted Answer

Binding of one O$$_2$$ molecule increases the affinity for subsequent O$$_2$$ molecules.

Question 14

Which of the following factors can shift the oxygen dissociation curve of hemoglobin to the right, promoting oxygen release in tissues?

Accepted Answer

Increase in 2,3-bisphosphoglycerate (BPG) concentration

Question 15

The Bohr effect describes how:

Accepted Answer

Decreased pH (increased H$$^+) $$promotes O$$_2$$ release from hemoglobin.

Question 16

Which of the following is TRUE regarding the T (tense) and R (relaxed) states of hemoglobin?

Accepted Answer

The R state is stabilized by O$$_2$$ binding and has a higher affinity for O$$_2.$$

Question 17

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

Accepted Answer

Fibrous proteins have parallel polypeptide chains and play structural roles, while globular proteins are more spherical and often have catalytic functions.

Question 18

Which of the following is a covalent interaction that stabilizes protein tertiary or quaternary structure?

Accepted Answer

Disulfide bonds between cysteine side chains

Question 19

A protein is exposed to sodium dodecyl sulfate (SDS) and β-mercaptoethanol. What is the expected result?

Accepted Answer

Disruption of hydrophobic interactions and reduction of disulfide bonds, leading to denaturation.

Protein Structure and Function: A Biochemistry Study Guide

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