Questions and Ansẉers
2026\2027 update
1. Which of the following is the general structure of an alpha-amino
acid?
A) A central carbon bonded to an amino group, a carboxyl group, a
hydrogen atom, and an R group.
B) A central carbon bonded to two amino groups and a carboxyl
group.
C) A central carbon bonded to an amino group, two carboxyl
groups, and an R group.
D) A central carbon bonded to a hydroxyl group, an amino group,
and an R group.
Answer: A
2. How many standard amino acids are commonly incorporated into
proteins during translation?
A) 15
B) 20
C) 22
D) 64
Answer: B
3. Which amino acid is achiral (lacks a chiral center)?
,A) Alanine
B) Valine
C) Glycine
D) Proline
Answer: C
4. Which amino acid contains a secondary amine group rather than a
primary amine group, forming a cyclic structure?
A) Tryptophan
B) Histidine
C) Proline
D) Tyrosine
Answer: C
5. Which of the following amino acids is classified as acidic?
A) Arginine
B) Aspartate
C) Asparagine
D) Alanine
Answer: B
6. Which pair of amino acids are positively charged (basic) at
physiological pH (7.4)?
A) Lysine and Arginine
B) Glutamate and Aspartate
C) Histidine and Glutamine
, D) Serine and Threonine
Answer: A
7. Which amino acid side chain can form disulfide bonds?
A) Methionine
B) Serine
C) Cysteine
D) Glycine
Answer: C
8. Which of the following amino acids is aromatic?
A) Phenylalanine
B) Leucine
C) Isoleucine
D) Valine
Answer: A
9. At a pH equal to its isoelectric point (pI), an amino acid in
solution will:
A) Have a net positive charge.
B) Have a net negative charge.
C) Have no net electrical charge.
D) Precipitate out of solution completely.
Answer: C