Question 1

Which of the following best describes the structure of an amino acid at physiological pH?

Accepted Answer

A central carbon bonded to a hydrogen, a carboxylate group, an ammonium group, and an R group.

Question 2

Which amino acid is classified as nonpolar due to its R group being a hydrogen atom?

Accepted Answer

Glycine

Question 3

At physiological pH, what is the net charge of a typical amino acid?

Accepted Answer

Zero

Question 4

Which amino acid has a polar neutral R group containing a hydroxyl group?

Accepted Answer

Serine

Question 5

What is the three-letter abbreviation for aspartate?

Accepted Answer

Asp

Question 6

Which amino acid is classified as polar acidic due to its carboxylate R group?

Accepted Answer

Aspartate

Question 7

Which amino acid is classified as polar basic due to its ammonium R group?

Accepted Answer

Lysine

Question 8

What is the one-letter abbreviation for phenylalanine?

Accepted Answer

F

Question 9

Which protein function is exemplified by hemoglobin?

Accepted Answer

Transport

Question 10

Cystinuria is a disease characterized by the formation of stones in urine due to high concentrations of which compound?

Accepted Answer

Cystine

Question 11

Which equation correctly represents the ionized form of an amino acid at physiological pH?

Accepted Answer

$$\mathrm{RCH(NH_3$^+)COO^-}$$

Question 12

Which amino acid has a nonpolar aromatic R group?

Accepted Answer

Phenylalanine

Question 13

A patient with sickle cell anemia has a mutation in the hemoglobin protein. Which property of proteins is most directly affected by this mutation?

Accepted Answer

The order of amino acids

Question 14

Which amino acid is most likely to be found in the interior of a protein due to its hydrophobic nature?

Accepted Answer

Leucine

Question 15

Which of the following best explains why proteins can have such diverse functions in the body?

Accepted Answer

Proteins are polymers made from 20 different amino acids, each with unique properties.

Question 16

Which amino acid contains a thiol group in its R group?

Accepted Answer

Cysteine

Question 17

Which amino acid is cyclic due to its R group bonding to the nitrogen atom attached to the alpha carbon?

Accepted Answer

Proline

Question 18

Which amino acid is most likely to be involved in the formation of disulfide bonds in proteins?

Accepted Answer

Cysteine

Question 19

Which amino acid has a one-letter abbreviation that is not the first letter of its name?

Accepted Answer

Tyrosine (Y)

Question 20

A protein's function as an enzyme is most directly related to which property?

Accepted Answer

The sequence and structure of its amino acids

Amino Acids and Proteins: Structure, Classification, and Biological Significance

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