Question 1

Which of the following best describes a zwitterion form of an amino acid at physiological pH?

Accepted Answer

The amino group is protonated (−NH3+) and the carboxyl group is deprotonated (−COO−).

Question 2

Which type of interaction is primarily responsible for stabilizing the secondary structure of proteins such as the alpha helix and beta-pleated sheet?

Accepted Answer

Hydrogen bonds

Question 3

Amino acids with side chains containing only hydrocarbons are classified as:

Accepted Answer

Nonpolar

Question 4

Which of the following is a correct description of a peptide bond?

Accepted Answer

An amide bond formed between the carboxyl group of one amino acid and the amino group of another

Question 5

Which protein structure level is directly affected by the hydrolysis of a protein?

Accepted Answer

Primary structure

Question 6

Which of the following is a real-life example of protein denaturation by heat?

Accepted Answer

Hard-boiling an egg

Question 7

Which of the following amino acids is classified as polar, neutral?

Accepted Answer

Threonine

Question 8

What is the main function of hemoglobin in the human body?

Accepted Answer

Transport oxygen

Question 9

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

Accepted Answer

The three-dimensional folding of a single polypeptide chain stabilized by interactions between R groups

Question 10

Which of the following is NOT a typical interaction stabilizing the tertiary structure of proteins?

Accepted Answer

Peptide bonds

Question 11

A protein that consists of two or more polypeptide chains exhibits which level of protein structure?

Accepted Answer

Quaternary

Question 12

Which of the following is a correct product of the complete hydrolysis of the tripeptide Ala-Ser-Val?

Accepted Answer

Alanine, serine, and valine

Question 13

Which of the following best explains why heavy metal ions can denature proteins?

Accepted Answer

They react with disulfide bonds, forming insoluble metal-sulfur bonds.

Question 14

Which of the following is a function of enzymes in the body?

Accepted Answer

Catalyze biochemical reactions

Question 15

Which of the following best describes the effect of denaturation on a protein?

Accepted Answer

It disrupts secondary, tertiary, and quaternary structures without breaking peptide bonds.

Question 16

Which of the following is a correct example of a salt bridge in a protein's tertiary structure?

Accepted Answer

An ionic interaction between a lysine (basic) and aspartic acid (acidic) side chain

Question 17

Which of the following best describes the role of collagen in the body?

Accepted Answer

Provides structural support in tendons and cartilage

Question 18

Which of the following amino acids would most likely be found on the interior of a globular protein in an aqueous environment?

Accepted Answer

Leucine

Question 19

Which of the following statements about the primary structure of a protein is correct?

Accepted Answer

It is the sequence of amino acids joined by peptide bonds.

Question 20

Which of the following best explains why sickle cell anemia is caused by a single amino acid substitution in hemoglobin?

Accepted Answer

The substitution alters the primary structure, which changes the protein's folding and function.

Ch. 19

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