Question 1

Which of the following best describes the chemical reaction that forms a peptide bond between two amino acids?

Accepted Answer

A condensation reaction that releases a water molecule when the carboxyl group of one amino acid reacts with the amino group of another.

Question 2

A mutation changes a single amino acid in the primary structure of hemoglobin, causing the protein to stick to others and form fibers. This is an example of:

Accepted Answer

A change in primary structure that leads to altered quaternary structure and function.

Question 3

Which of the following R-groups would most likely be found in the interior of a folded protein in an aqueous environment?

Accepted Answer

A nonpolar R-group such as leucine.

Question 4

What type of bond is primarily responsible for stabilizing the secondary structure of proteins?

Accepted Answer

Hydrogen bonds between the carbonyl and amino groups of the backbone.

Question 5

Which of the following statements about protein folding is TRUE?

Accepted Answer

Molecular chaperones assist in proper folding by preventing inappropriate interactions.

Question 6

A protein is found to consist of two identical polypeptide subunits. This protein is best described as a:

Accepted Answer

Homodimer with quaternary structure.

Question 7

Which of the following best explains why enzymes are effective biological catalysts?

Accepted Answer

They hold substrates in a precise orientation at the active site, lowering activation energy.

Question 8

Given the following amino acid side chain: $-CH_2-SH$, which type of interaction can it form in a protein's tertiary structure?

Accepted Answer

Disulfide bond with another cysteine side chain.

Question 9

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

Accepted Answer

Storing genetic information.

Question 10

A researcher denatures a protein by heating it. Which level(s) of protein structure are most likely disrupted?

Accepted Answer

Secondary, tertiary, and quaternary structures.

Question 11

Which of the following best describes a nonpolar amino acid?

Accepted Answer

Its side chain contains only carbon and hydrogen atoms.

Question 12

Which of the following scenarios would most likely result in a protein losing its function?

Accepted Answer

A change in the pH that causes the protein to denature.

Question 13

Which of the following is a property of the peptide bond?

Accepted Answer

It is a covalent bond formed by a condensation reaction.

Question 14

A protein's tertiary structure is stabilized by all of the following EXCEPT:

Accepted Answer

Peptide bonds between amino acids.

Question 15

Which of the following best explains why prions are infectious?

Accepted Answer

They induce normal proteins to adopt an abnormal, disease-causing conformation.

Question 16

Which of the following is true about the directionality of a polypeptide chain?

Accepted Answer

The N-terminus is always written on the left by convention.

Question 17

Which of the following best describes the role of molecular chaperones in cells?

Accepted Answer

They assist in the proper folding of proteins by preventing inappropriate interactions.

Question 18

Which of the following interactions is unique to the quaternary structure of proteins?

Accepted Answer

Interactions between multiple polypeptide subunits.

Question 19

A protein is found to have a region that binds specifically to glucose and catalyzes its breakdown. This region is most likely:

Accepted Answer

The active site of an enzyme.

Question 20

Which of the following best explains why a single amino acid substitution can drastically affect protein function?

Accepted Answer

It can alter the primary structure, which determines all higher levels of structure and function.

Protein Structure and Function: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards