Question 1

Which of the following best describes a peptide bond?

Accepted Answer

An amide bond formed between the $\mathrm{COO^-}$ group of one amino acid and the $\mathrm{NH_3^+}$ group of the next amino acid.

Question 2

A protein is defined as a polypeptide containing how many amino acids?

Accepted Answer

50 or more amino acids

Question 3

Which of the following foods is considered a complete protein source?

Accepted Answer

Eggs

Question 4

Which of the following is NOT an essential amino acid for adults?

Accepted Answer

Glycine

Question 5

What is the primary structure of a protein?

Accepted Answer

The particular sequence of amino acids held together by peptide bonds.

Question 6

If a tripeptide has the sequence Glu-His-Pro, which amino acid is at the N-terminus?

Accepted Answer

Glutamic acid

Question 7

Which of the following statements about essential amino acids is TRUE?

Accepted Answer

They must be obtained from dietary proteins.

Question 8

What type of bond is formed when the carboxyl group of one amino acid reacts with the amino group of another?

Accepted Answer

Peptide bond

Question 9

Which of the following is the correct three-letter abbreviation for the tetrapeptide Alanylleucylcysteinylmethionine?

Accepted Answer

Ala-Leu-Cys-Met

Question 10

A patient is diagnosed with a deficiency in lysine. Which dietary recommendation would best address this deficiency?

Accepted Answer

Consume more eggs, milk, and fish.

Question 11

How many different tripeptides can be formed from two glycines and one alanine?

Accepted Answer

Three

Question 12

Which of the following is the correct order of amino acids in the peptide Gly-Ala-Gly?

Accepted Answer

Glycine, Alanine, Glycine

Question 13

Which amino acid is at the C-terminus of the peptide Pro-His-Met?

Accepted Answer

Methionine

Question 14

Which of the following is a consequence of altering the primary structure of a protein?

Accepted Answer

The protein may lose its biological activity.

Question 15

Which of the following amino acids is NOT essential for adults?

Accepted Answer

Serine

Question 16

What is the result of the reaction between the $\mathrm{COO^-}$ group of one amino acid and the $\mathrm{NH_3^+}$ group of another?

Accepted Answer

Formation of a peptide bond and water

Question 17

Which of the following is a tetrapeptide?

Accepted Answer

Ala-Leu-Cys-Met

Question 18

Which statement best explains why plant proteins are considered incomplete?

Accepted Answer

They are deficient in one or more essential amino acids.

Question 19

Which sequence of amino acids is required for the thyroid hormone that stimulates thyroxin release?

Accepted Answer

Glu-His-Pro

Question 20

Which of the following is the correct structure for the dipeptide Ser-Thr?

Accepted Answer

$\mathrm{H_3N^+-CH_2OH-CH-CO-NH-CH(CH_3)-CH-COO^-}$

Amino Acids, Proteins, and Enzymes: Primary Structure and Essential Amino Acids

Study Guide - Practice Questions