Question 1

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

Accepted Answer

An amide bond formed between the carboxyl group of one amino acid and the amino group of another

Question 2

What is the correct sequence for naming a peptide composed of glycine, serine, and methionine from N-terminus to C-terminus?

Accepted Answer

Glycylserylmethionine

Question 3

Which of the following statements about the primary structure of a protein is TRUE?

Accepted Answer

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

Question 4

A tripeptide is formed from alanine, glycine, and serine. Which of the following is a possible name for this tripeptide?

Accepted Answer

Alanylglycylserine

Question 5

Which of the following is TRUE regarding essential amino acids?

Accepted Answer

They must be obtained from dietary proteins

Question 6

Eggs, milk, meat, and fish are considered complete proteins because:

Accepted Answer

They contain all of the essential amino acids

Question 7

Which of the following best describes the N-terminus of a peptide?

Accepted Answer

The end of the peptide with a free amino group

Question 8

What type of reaction forms a peptide bond between two amino acids?

Accepted Answer

Condensation (dehydration synthesis)

Question 9

Which of the following is a correct three-letter abbreviation for a tripeptide composed of glycine, glycine, and alanine, with glycine at the N-terminus?

Accepted Answer

$$\mathrm{Gly-Gly-Ala}$$

Question 10

Insulin was the first protein to have its primary structure determined. Which of the following is TRUE about insulin's structure?

Accepted Answer

It has two polypeptide chains linked by disulfide bonds

Question 11

Which of the following best explains why the sequence of amino acids in a protein is important?

Accepted Answer

It determines the protein's biological activity and function

Question 12

A peptide bond forms between which two functional groups of adjacent amino acids?

Accepted Answer

Amino group and carboxyl group

Question 13

Which of the following is a consequence of a change in the primary structure of a protein?

Accepted Answer

The protein may lose its biological activity

Question 14

Which of the following foods is most likely to be deficient in one or more essential amino acids?

Accepted Answer

Beans

Question 15

What is the minimum number of amino acids in a polypeptide for it to be considered a protein?

Accepted Answer

50

Question 16

Which of the following is a correct description of a dipeptide?

Accepted Answer

A molecule formed from two amino acids joined by a peptide bond

Question 17

Which of the following is a correct statement about incomplete proteins?

Accepted Answer

They are typically found in plant sources

Question 18

During the formation of a peptide bond, what molecule is released as a byproduct?

Accepted Answer

Water ($$\mathrm{H_2O})$$

Question 19

Which of the following best describes the C-terminus of a peptide?

Accepted Answer

The end of the peptide with a free carboxyl group

Question 20

Which of the following is the correct order for the steps in drawing the structure of a tripeptide?

Accepted Answer

Draw each amino acid, remove atoms to form peptide bonds, connect residues with peptide bonds

Amino Acids and Proteins: Primary Structure and Peptide Formation

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