Question 1

Which of the following best explains why proteins are considered the most structurally complex biological molecules?

Accepted Answer

They are made of unbranched polymers of 20 different amino acids, folded into complex three-dimensional shapes.

Question 2

A scientist is studying a protein that helps transport oxygen in the blood. Which class of protein does this molecule belong to?

Accepted Answer

Transport protein

Question 3

Which of the following is NOT a function performed by proteins in living organisms?

Accepted Answer

Storing genetic information

Question 4

Amino acids are classified as acidic, basic, polar, or nonpolar based on the properties of which part of their structure?

Accepted Answer

The R group (side chain)

Question 5

Which of the following amino acids would most likely be found in the interior of a globular protein, away from water?

Accepted Answer

An amino acid with a nonpolar R group

Question 6

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 7

Which of the following correctly 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 8

Which level of protein structure is primarily determined by the sequence of amino acids?

Accepted Answer

Primary structure

Question 9

Which type of interaction is responsible for stabilizing the alpha helix and beta pleated sheet structures in proteins?

Accepted Answer

Hydrogen bonds between backbone atoms

Question 10

A mutation causes a cysteine residue to be replaced by serine in a protein. Which type of stabilizing interaction is most likely to be affected?

Accepted Answer

Disulfide bridge formation

Question 11

Hemoglobin is a protein composed of four polypeptide subunits. Which level of protein structure does this represent?

Accepted Answer

Quaternary structure

Question 12

Which of the following best describes the process by which a peptide bond is formed?

Accepted Answer

A hydroxyl group is removed from the carboxyl end of one amino acid and a hydrogen atom from the amino group of another, forming water.

Question 13

Which of the following is a real-world example of a protein with quaternary structure?

Accepted Answer

Collagen in connective tissue

Question 14

If you substitute alanine for glycine in a protein, what change to the protein's structure would you expect?

Accepted Answer

Much change, since one has a large side chain and the other a small side chain

Question 15

Which of the following correctly lists the four levels of protein structure from simplest to most complex?

Accepted Answer

Primary, secondary, tertiary, quaternary

Question 16

Which of the following equations represents the dehydration reaction that forms a peptide bond between two amino acids?

Accepted Answer

$$\mathrm{Amino\ acid}_1 + \mathrm{Amino\ acid}_2 \rightarrow \mathrm{Dipeptide} + H_2O$$

Question 17

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

Accepted Answer

Phosphodiester bonds between nucleotides

Question 18

A protein is found to have a mutation that replaces a nonpolar R group with a charged R group. What is the most likely effect on the protein's structure?

Accepted Answer

The protein may misfold due to altered hydrophobic interactions.

Question 19

Which of the following best describes the role of antibodies in the immune system?

Accepted Answer

They bind to and help destroy viruses and bacteria.

Proteins: Structure, Function, and Diversity in Biology

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