Question 1

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

Accepted Answer

The sequence of amino acids joined by peptide bonds.

Question 2

A mutation causes a polar amino acid to be replaced by a nonpolar amino acid in the interior of a protein. What is the most likely effect on the protein's tertiary structure?

Accepted Answer

The protein's hydrophobic core will be destabilized, possibly leading to misfolding.

Question 3

Which type of bond is primarily responsible for stabilizing the secondary structure of proteins such as alpha helices and beta sheets?

Accepted Answer

Hydrogen bonds

Question 4

What is the chemical reaction called that joins two amino acids together, and what is the byproduct?

Accepted Answer

Dehydration synthesis; water

Question 5

Which amino acid is most likely to form a disulfide bond, and why are these bonds important?

Accepted Answer

Cysteine; they stabilize tertiary and quaternary structures.

Question 6

A protein is exposed to high heat and loses its functional shape. What is this process called, and what type of bonds are primarily disrupted?

Accepted Answer

Denaturation; noncovalent bonds such as hydrogen bonds and van der Waals forces

Question 7

Which of the following best explains why hemoglobin and collagen, both proteins, have such different functions?

Accepted Answer

They have different sequences of amino acids, leading to different structures.

Question 8

Which of the following amino acids would most likely be found on the exterior of a soluble protein in the cytoplasm?

Accepted Answer

Glutamine

Question 9

A peptide bond forms between which two functional groups of adjacent amino acids?

Accepted Answer

The amine group of one and the carboxyl group of another

Question 10

Which of the following changes is most likely to disrupt the secondary structure of a protein without breaking peptide bonds?

Accepted Answer

A change in pH that disrupts hydrogen bonding

Question 11

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

Accepted Answer

The association of multiple polypeptide subunits into a functional protein

Question 12

Which of the following is a real-life example of a protein whose function depends on its quaternary structure?

Accepted Answer

Hemoglobin transporting oxygen in blood

Question 13

Which of the following statements about the alpha helix is TRUE?

Accepted Answer

The alpha helix is stabilized by hydrogen bonds between the backbone atoms.

Question 14

Which process is responsible for breaking down a protein polymer into its individual amino acids?

Accepted Answer

Hydrolysis

Question 15

Which of the following amino acids is most likely to be involved in forming ionic bonds within a protein structure?

Accepted Answer

Aspartic acid

Question 16

A protein is exposed to a high salt concentration. Which level(s) of protein structure are most likely to be affected?

Accepted Answer

Secondary, tertiary, and quaternary structures

Question 17

Which of the following best explains why proteins can have such a wide variety of functions in cells?

Accepted Answer

Proteins are made of 20 different amino acids that can be arranged in countless sequences.

Question 18

Which of the following is a correct description of a zwitterion as it relates to amino acids?

Accepted Answer

An amino acid with both a positive and negative charge at neutral pH.

Question 19

Which of the following is most likely to occur if a protein's tertiary structure is disrupted but its primary structure remains intact?

Accepted Answer

The protein will lose its function but can potentially refold if conditions return to normal.

The Chemistry of Life: Structure and Function of Proteins 2/18

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