BIOCHEMISTRY CHAPTER 4 5 6 TEST BANK QUESTIONS EXAM 2
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Which of the following amino acids does NOT have an ionizable side chain?
A) Asp
B) Cys
C) Lys
D) His
E) Asn - CORRECT ANSWER -E
Which of the following amino acids has an uncharged polar side chain at pH
7.0?
A) Arg
B) Thr
C) Glu
D) Pro
,E) Ile - CORRECT ANSWER -B
What is the structure of Asn? - CORRECT ANSWER -
The ionization of amino acids depends on the pH and the pKas of the
ionizable groups. The pK1 and pK2 for the amino acid (Asn shown in
previous question) are 2.1 and 8.8, respectively. At what pH is the amino
acid ionized predominantly as shown? - CORRECT ANSWER -pH 1.0
The pK1, pK2, and pKR for the amino acid arginine are 1.8, 9.0, and 12.5,
respectively. At pH 7.0 arginine would be charged predominantly as
follows: - CORRECT ANSWER -α-carboxylate-1, α-amino+1,
guanidino+1, net charge +1
The pK1, pK2, and pKR for the amino acid aspartic acid are 2.0, 9.9, and
3.9, respectively. At pH 7.0, aspartic acid would be charged predominantly
as follows: - CORRECT ANSWER -α-carboxylate -1, α-amino +1, β-
Carboxylate -1, Net charge -1
The pK 1 , pK 2 , and pK R for the amino acid glutamate are 2.1, 9.5, and
4.1, respectively. At
,pH 11.0, glutamate would be charged predominantly as follows: -
CORRECT ANSWER -α-carboxylate −1, α-amino 0, γ-carboxylate −1, net
charge −2
The pK 1 , pK 2 , and pK R for the amino acid histidine are 1.8, 9.3, and 6.0,
respectively. At pH
4.0 would be charged predominantly as follows: - CORRECT ANSWER -
α-carboxylate −1, α-amino +1, imidazole +1, net charge +1
The pK 1 , pK 2 , and pK R for the amino acid cysteine are 1.9, 10.7, and
8.4, respectively. At pH
5.0, cysteine would be charged predominantly as follows: - CORRECT
ANSWER -α-carboxylate −1, α-amino +1, sulfhydryl 0, net charge 0
The pK 1 , pK 2 , and pK R for the amino acid lysine are 2.2, 9.1, and 10.5,
respectively. At pH
1.0, lysine would be charged predominantly as follows: - CORRECT
ANSWER -α-carboxylate 0, α-amino +1, ε-amino +1, net charge +2
While proteins are usually composed of linear chains of amino acids,
branched chains of amino acids and internally cross-linked chains can be
, found in certain proteins. Polypeptide chains are most commonly linked to
each other through - CORRECT ANSWER -Disulfide Bonds
The disulfide bond betwee two cysteine molecules
A) is a peptide bond.
B) is an ionic interaction that is stable at physiological pH.
C) is a covalent bond formed by oxidation.
D) is a hydrogen bond between the two sulfhydryl groups.
E) is a dipole-dipole interaction. - CORRECT ANSWER -D) Is covalent
bond formed by oxidation
The tripeptide glycylarginylglutamate contains four ionizable groups with
pKas of 2.1, 4.1, 9.8, and 12.5. Calculate the pI for this molecule -
CORRECT ANSWER -7.0
The tripeptide alanyllysylaspartate contains four ionizable groups with pKas
of 2.0, 3.9, 9.9, and 10.5. Calculate the pI for this molecule.
A) 3.0
BIOCHEMISTRY COURSE 2025/2026 | QUESTION BANK | VERIFIED
QUESTIONS AND ANSWERS GRADED A+ | METABOLIC PATHWAYS,
ENZYMES & MOLECULAR PROCESSES STUDY GUIDE | GUARANTEED
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Which of the following amino acids does NOT have an ionizable side chain?
A) Asp
B) Cys
C) Lys
D) His
E) Asn - CORRECT ANSWER -E
Which of the following amino acids has an uncharged polar side chain at pH
7.0?
A) Arg
B) Thr
C) Glu
D) Pro
,E) Ile - CORRECT ANSWER -B
What is the structure of Asn? - CORRECT ANSWER -
The ionization of amino acids depends on the pH and the pKas of the
ionizable groups. The pK1 and pK2 for the amino acid (Asn shown in
previous question) are 2.1 and 8.8, respectively. At what pH is the amino
acid ionized predominantly as shown? - CORRECT ANSWER -pH 1.0
The pK1, pK2, and pKR for the amino acid arginine are 1.8, 9.0, and 12.5,
respectively. At pH 7.0 arginine would be charged predominantly as
follows: - CORRECT ANSWER -α-carboxylate-1, α-amino+1,
guanidino+1, net charge +1
The pK1, pK2, and pKR for the amino acid aspartic acid are 2.0, 9.9, and
3.9, respectively. At pH 7.0, aspartic acid would be charged predominantly
as follows: - CORRECT ANSWER -α-carboxylate -1, α-amino +1, β-
Carboxylate -1, Net charge -1
The pK 1 , pK 2 , and pK R for the amino acid glutamate are 2.1, 9.5, and
4.1, respectively. At
,pH 11.0, glutamate would be charged predominantly as follows: -
CORRECT ANSWER -α-carboxylate −1, α-amino 0, γ-carboxylate −1, net
charge −2
The pK 1 , pK 2 , and pK R for the amino acid histidine are 1.8, 9.3, and 6.0,
respectively. At pH
4.0 would be charged predominantly as follows: - CORRECT ANSWER -
α-carboxylate −1, α-amino +1, imidazole +1, net charge +1
The pK 1 , pK 2 , and pK R for the amino acid cysteine are 1.9, 10.7, and
8.4, respectively. At pH
5.0, cysteine would be charged predominantly as follows: - CORRECT
ANSWER -α-carboxylate −1, α-amino +1, sulfhydryl 0, net charge 0
The pK 1 , pK 2 , and pK R for the amino acid lysine are 2.2, 9.1, and 10.5,
respectively. At pH
1.0, lysine would be charged predominantly as follows: - CORRECT
ANSWER -α-carboxylate 0, α-amino +1, ε-amino +1, net charge +2
While proteins are usually composed of linear chains of amino acids,
branched chains of amino acids and internally cross-linked chains can be
, found in certain proteins. Polypeptide chains are most commonly linked to
each other through - CORRECT ANSWER -Disulfide Bonds
The disulfide bond betwee two cysteine molecules
A) is a peptide bond.
B) is an ionic interaction that is stable at physiological pH.
C) is a covalent bond formed by oxidation.
D) is a hydrogen bond between the two sulfhydryl groups.
E) is a dipole-dipole interaction. - CORRECT ANSWER -D) Is covalent
bond formed by oxidation
The tripeptide glycylarginylglutamate contains four ionizable groups with
pKas of 2.1, 4.1, 9.8, and 12.5. Calculate the pI for this molecule -
CORRECT ANSWER -7.0
The tripeptide alanyllysylaspartate contains four ionizable groups with pKas
of 2.0, 3.9, 9.9, and 10.5. Calculate the pI for this molecule.
A) 3.0
