Question 1

Which of the following statements about the stereochemistry of amino acids is CORRECT?

Accepted Answer

Glycine is the only protein-derived amino acid that is achiral.

Question 2

Which amino acid contains a sulfur atom in its side chain?

Accepted Answer

Methionine

Question 3

A solution contains only glycine at pH 7.0. What is the net charge of the majority of glycine molecules?

Accepted Answer

0

Question 4

Which amino acid has an indole ring in its side chain and absorbs UV light strongly at 280 nm?

Accepted Answer

Tryptophan

Question 5

What is the three-letter abbreviation for the amino acid with the one-letter code 'Q'?

Accepted Answer

Gln

Question 6

Which of the following amino acids has a side chain that can form a disulfide bond under oxidizing conditions?

Accepted Answer

Cysteine

Question 7

At pH 7.0, which group on a typical amino acid is almost completely deprotonated?

Accepted Answer

α-carboxyl group

Question 8

Which equation is used to calculate the isoelectric point (pI) of an amino acid with only two ionizable groups?

Accepted Answer

$$pI = \frac{pK_1$ + pK_2$}{2}$$

Question 9

Which amino acid is most likely to be found in the active site of an enzyme that requires proton transfer at physiological pH?

Accepted Answer

Histidine

Question 10

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

Accepted Answer

α-carboxyl group and α-amino group

Question 11

Which amino acid has a side chain that is a carboxylate ion at pH 7.0?

Accepted Answer

Aspartic acid

Question 12

What is the correct one-letter abbreviation for tryptophan?

Accepted Answer

W

Question 13

Which property of the peptide bond restricts rotation and gives it partial double bond character?

Accepted Answer

Resonance between the carbonyl oxygen and the amide nitrogen

Question 14

Which amino acid contains a guanidino group in its side chain, making it a strong base?

Accepted Answer

Arginine

Question 15

If a peptide has the sequence Gly-Ala-Ser, which end is the amino-terminal?

Accepted Answer

Glycine

Question 16

Which of the following amino acids is classified as nonpolar and aromatic?

Accepted Answer

Phenylalanine

Question 17

Which equation describes the relationship between absorbance and concentration in UV-visible spectrophotometry?

Accepted Answer

$$A = \varepsilon \cdot c \cdot l$$

Question 18

Which amino acid has a side chain with a hydroxyl group bonded to an aliphatic hydrocarbon?

Accepted Answer

Serine

Question 19

Which of the following is TRUE regarding the ionization state of the α-amino group at pH 7.0?

Accepted Answer

It is almost completely protonated and carries a +1 charge.

Question 20

Which amino acid is most likely to be found in collagen due to its unique secondary structure?

Accepted Answer

Proline

Amino Acids: Structure, Classification, and Properties Ch 3

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