Question 1

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

Accepted Answer

Peptide bond

Question 2

What is the repeating backbone structure found in polypeptides?

Accepted Answer

$N-C_\alpha-C$

Question 3

Which amino acid is most likely to form a disulfide bridge in proteins?

Accepted Answer

Cysteine

Question 4

During peptide bond formation, what molecule is lost as a byproduct?

Accepted Answer

$H_2O$

Question 5

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

Accepted Answer

From the N-terminus to the C-terminus

Question 6

Which secondary structure is stabilized by hydrogen bonds between the carbonyl oxygen of one residue and the amide hydrogen of the residue four positions ahead?

Accepted Answer

α-helix

Question 7

What is the approximate molecular weight of a protein containing 150 amino acids?

Accepted Answer

$16,500\ \mathrm{gmol}^{-1}$

Question 8

Which of the following amino acids is most likely to disrupt an α-helix due to its rigid cyclic structure?

Accepted Answer

Proline

Question 9

In a β-sheet, hydrogen bonds are formed between:

Accepted Answer

Backbone atoms of adjacent strands

Question 10

Which statement about peptide bonds is correct?

Accepted Answer

Peptide bonds are planar due to resonance between the carbonyl and amide nitrogen

Question 11

Which of the following is a consequence of peptide bond resonance?

Accepted Answer

Restricted rotation around the C-N bond

Question 12

Which type of secondary structure is characterized by side chains projecting outward from the helical axis?

Accepted Answer

α-helix

Question 13

What is the main stabilizing force in antiparallel β-sheets?

Accepted Answer

Hydrogen bonds between backbone atoms of adjacent strands

Question 14

Which of the following best describes a reverse turn in protein structure?

Accepted Answer

A loop containing 5 residues or less, stabilized by H-bonding (i to i+3)

Question 15

Which amino acid is most commonly found at the ends of α-helices due to its flexibility?

Accepted Answer

Glycine

Question 16

Which of the following is true regarding the dipole of an α-helix?

Accepted Answer

The N-terminus is positively charged and the C-terminus is negatively charged

Question 17

Which of the following is a function of knowing the primary sequence of a protein?

Accepted Answer

It allows prediction of the protein's 3-D structure

Question 18

Which of the following is true about the formation of cystine from cysteine?

Accepted Answer

It involves the oxidation of two cysteine residues to form a disulfide bond

Question 19

Which of the following is NOT a regular secondary structure found in proteins?

Accepted Answer

Random coil

Question 20

A protein is found to have multiple polypeptide chains associated together. What level of protein structure does this represent?

Accepted Answer

Quaternary structure

Protein Three-Dimensional Structure: Primary and Secondary Structures

Study Guide - Practice Questions

Study Guide - Flashcards