Question 1

A mutation causes a single amino acid substitution in the primary structure of hemoglobin. Which level(s) of protein structure could be affected by this change?

Accepted Answer

All levels: primary, secondary, tertiary, and quaternary structures.

Question 2

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

Accepted Answer

A nonpolar R-group such as leucine.

Question 3

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

Accepted Answer

Hydrogen bonds between backbone atoms.

Question 4

A protein is denatured by heat. Which of the following best explains why the protein loses its function?

Accepted Answer

Heat disrupts non-covalent interactions, causing the protein to lose its three-dimensional shape.

Question 5

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

Accepted Answer

They facilitate proper protein folding by preventing inappropriate interactions.

Question 6

Which of the following amino acids would you expect to find at the active site of an enzyme that catalyzes a reaction involving a negatively charged substrate?

Accepted Answer

Amino acids with positively charged R-groups such as arginine.

Question 7

Which of the following statements about prions is correct?

Accepted Answer

Prions are infectious proteins that can induce normal proteins to misfold.

Question 8

Which of the following best explains why proteins are considered the most diverse class of biological molecules?

Accepted Answer

They have a limitless number of primary structures due to 20 different amino acids and variable lengths.

Question 9

A scientist isolates a protein that consists of two identical polypeptide subunits. What is the best description of this protein’s quaternary structure?

Accepted Answer

It is a homodimer.

Question 10

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

Accepted Answer

Hydrogen bonds between backbone atoms.

Question 11

Which of the following best describes the directionality of a polypeptide chain?

Accepted Answer

It is synthesized from the N-terminus to the C-terminus.

Question 12

Which of the following is a real-world example of how a single amino acid change can affect protein function?

Accepted Answer

The sickling of red blood cells in sickle cell anemia due to a change in hemoglobin’s primary structure.

Question 13

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 the activation energy.

Question 14

A protein is found to have a mutation that replaces a cysteine with a serine. Which type of interaction is most likely disrupted?

Accepted Answer

Disulfide bond formation.

Question 15

Which of the following best describes the effect of water on the folding of a protein with both hydrophobic and hydrophilic R-groups?

Accepted Answer

Hydrophobic R-groups cluster together inside the protein, while hydrophilic R-groups interact with water on the outside.

Question 16

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

Accepted Answer

Storing genetic information.

Question 17

Which of the following best describes the relationship between protein structure and function?

Accepted Answer

Protein function is determined by its three-dimensional structure, which is determined by its amino acid sequence.

Question 18

Which of the following statements about the flexibility of polypeptide chains is correct?

Accepted Answer

Single bonds on either side of the peptide bond can rotate, allowing the chain to bend and fold.

Protein Structure and Function: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards