Question 1

Which of the following statements best explains why amino acids are soluble in water?

Accepted Answer

The ionized amino and carboxyl groups form charges that interact with water molecules.

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 affecting higher levels of protein structure and function.

Question 3

Which of the following R-groups would most likely be found in the interior of a protein, away from water?

Accepted Answer

A nonpolar R-group such as leucine.

Question 4

What type of bond forms between the carboxyl group of one amino acid and the amino group of another during protein synthesis?

Accepted Answer

Peptide bond

Question 5

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

Accepted Answer

Hydrogen bonds between backbone atoms forming alpha-helices and beta-pleated sheets.

Question 6

A protein is denatured by heat. What is the most likely consequence?

Accepted Answer

The protein will lose its three-dimensional structure and become nonfunctional.

Question 7

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

Accepted Answer

Hydrogen bonding between backbone atoms only

Question 8

A protein composed of two identical polypeptide subunits is best described as a:

Accepted Answer

Homodimer

Question 9

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 10

Which of the following is a real-world example of a prion disease caused by protein misfolding?

Accepted Answer

Mad cow disease

Question 11

Given the following amino acid side chain: $$\mathrm{CH_2CH_2COO^-}$$, how would you classify this amino acid?

Accepted Answer

Acidic (negatively charged)

Question 12

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

Accepted Answer

It has a free amino group at the N-terminus and a free carboxyl group at the C-terminus.

Question 13

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

Accepted Answer

Storing genetic information

Question 14

A scientist isolates a protein that only becomes functional after binding to a specific small molecule. This is an example of:

Accepted Answer

Protein folding being regulated by molecular interactions.

Question 15

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

Accepted Answer

They facilitate proper protein folding and prevent aggregation.

Question 16

Which of the following equations correctly represents the condensation reaction that forms a peptide bond?

Accepted Answer

$$\mathrm{Amino\ $$acid_1$$ + Amino\ $$acid_2$$ \rightarrow Dipeptide + H_2O}$$

Question 17

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

Accepted Answer

It is planar and rigid due to partial double-bond character.

Question 18

A protein with four different polypeptide subunits is best described as having:

Accepted Answer

Quaternary structure

Question 19

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

Accepted Answer

It can alter the protein's primary structure, which determines all higher levels of structure.

Question 20

Which of the following is a real-life example of a protein acting as a molecular machine?

Accepted Answer

The ribosome synthesizing proteins from amino acids

Protein Structure and Function: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards