Question 1

Which of the following amino acids does NOT have a chiral center?

Accepted Answer

Glycine

Question 2

At physiological pH ($$pH \approx 7.4$$), what is the net charge of glutamic acid?

Accepted Answer

$$-1$$

Question 3

Which amino acid side chain has a $$pK_a in $$the physiological pH range and is often involved in proton transfer during enzymatic catalysis?

Accepted Answer

Histidine

Question 4

Which of the following best describes a peptide bond?

Accepted Answer

An amide bond between the $$\alpha-$$carboxyl group of one amino acid and the $$\alpha-$$amino group of another

Question 5

Which of the following amino acids is most likely to be found on the surface of a soluble protein?

Accepted Answer

Aspartic acid

Question 6

At $$pH = 1$$, a polypeptide will be predominantly:

Accepted Answer

Positively charged

Question 7

Which codon serves as the start codon in eukaryotic translation?

Accepted Answer

AUG

Question 8

Which of the following enzymes cleaves peptide bonds on the carboxyl side of lysine and arginine residues?

Accepted Answer

Trypsin

Question 9

A conservative mutation in a protein sequence is best described as:

Accepted Answer

A change that does not significantly affect the structure or function of the protein

Question 10

Which of the following best explains why the $$pK_a of an $$amino acid side chain can change inside a protein?

Accepted Answer

The local environment, such as nearby charged groups, can stabilize or destabilize the ionized form

Question 11

Which of the following amino acids contains a thiol group in its side chain?

Accepted Answer

Cysteine

Question 12

Which of the following is a post-translational modification that increases the strength of collagen fibers?

Accepted Answer

4-hydroxyproline

Question 13

Which of the following statements about the zwitterionic form of amino acids is correct?

Accepted Answer

It predominates at physiological pH, with the amino group protonated and the carboxyl group deprotonated

Question 14

Which of the following amino acids is aromatic?

Accepted Answer

Tryptophan

Question 15

Which of the following best describes the process of translation?

Accepted Answer

The synthesis of a protein sequence from an mRNA template in the ribosome

Question 16

Which of the following amino acids is most likely to be found buried within the hydrophobic core of a globular protein?

Accepted Answer

Valine

Question 17

Which of the following is the correct one-letter code for asparagine?

Accepted Answer

N

Question 18

Which of the following best describes the role of disulfide bonds in proteins?

Accepted Answer

They stabilize the tertiary and quaternary structure by covalently linking cysteine residues

Question 19

Which of the following codons is a stop codon in the genetic code?

Accepted Answer

UGA

Question 20

Which of the following best describes a nonconservative mutation?

Accepted Answer

A mutation that changes the amino acid to one with very different properties, significantly affecting protein structure or function

Amino Acids, Peptides, and Protein Structure: Study Guide

Study Guide - Practice Questions