Question 1

Which of the following best describes a peptide bond in proteins?

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 with 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

Given the tripeptide abbreviation Pro-His-Met, which amino acid is at the N-terminus?

Accepted Answer

Proline

Question 6

Which statement about the primary structure of a protein is correct?

Accepted Answer

It is the particular sequence of amino acids held together by peptide bonds.

Question 7

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

Accepted Answer

3

Question 8

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

Accepted Answer

Ala-Leu-Cys-Met

Question 9

What is the product when the carboxyl group of one amino acid reacts with the amino group of another amino acid?

Accepted Answer

A peptide bond and water

Question 10

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

Accepted Answer

Glu-His-Pro

Question 11

If a peptide is formed from the amino acids glycine, serine, and methionine in that order, what is its three-letter abbreviation?

Accepted Answer

Gly-Ser-Met

Question 12

Which of the following is a consequence of an incorrect amino acid sequence in the primary structure of a protein?

Accepted Answer

The protein may lose its biological activity.

Question 13

Which of the following is true about incomplete proteins?

Accepted Answer

They are deficient in one or more essential amino acids.

Question 14

What is the general formula for the formation of a peptide bond between two amino acids?

Accepted Answer

$$\mathrm{R_1$-CH(NH_2$)-COOH + R_2$-CH(NH_2$)-COOH \rightarrow R_1$-CH(NH_2$)-CO-NH-CH(R_2$)-COOH + H_2O}$$

Question 15

Which amino acid is represented by the three-letter abbreviation 'Trp'?

Accepted Answer

Tryptophan

Question 16

Which of the following is a tetrapeptide?

Accepted Answer

Ala-Leu-Cys-Met

Question 17

Which process occurs during the formation of a peptide bond?

Accepted Answer

Dehydration (condensation)

Question 18

Which of the following amino acids must be obtained from the diet because it cannot be synthesized by the human body?

Accepted Answer

Lysine

Question 19

A dipeptide is formed from serine and threonine. Which of the following correctly describes the bond formed between them?

Accepted Answer

A peptide bond between the carboxyl group of serine and the amino group of threonine

Question 20

Which of the following statements about the sequence of amino acids in a protein is correct?

Accepted Answer

The specific sequence of amino acids determines the protein's biological activity.

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

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