BIOC 384 EVALUATION EXAM QUESTIONS AND
ANSWERS GRADED A+
✔✔What is the net reaction (1+2) shown below (???) andwhat is the ∆Gº' (???) for this
net reaction?
(1) NH4+ + Glutamate <-> Glutamine ∆Gº' = +14.2kJ/mol
(2) ATP <-> ADP + Pi ∆Gº' =-30.5 kJ/mol
(1 + 2) ????? <-> ??????? ∆Gº' = ????kJ/mol
A.ATP + Glutamate + NH4+ <-> Glutamine + ADP + Pi ∆Gº' = -16.3 kJ/mol
B.Glutamine + NH4+ <-> Glutamate + ATP ∆Gº' = -14.2 kJ/mol
C.NH4++ Glutamate + ADP + Pi <->Glutamine + ATP ∆Gº' = -30.5 kJ/mol
D.ATP + Glutamate + NH4+ <->Glutamine + ADP + Pi ∆Gº' = -44.7 kJ/mol
E.None of these answers are correct - ✔✔A.ATP + Glutamate + NH4+ <-> Glutamine +
ADP + Pi ∆Gº' = -16.3 kJ/mol
✔✔Is the circled group/atom a hydrogen bond donor or a hydrogen bond acceptor?
A. 1 is acceptor, 2 is acceptor, 3 is donor, 4 is donor
B. 1 is donor, 2 is acceptor, 3 is donor, 4 is acceptor
C. 1 is acceptor, 2 is donor, 3 is acceptor, 4 is donor
D. 1 is donor, 2 is donor, 3 is acceptor, 4 is donor
E. 1 is acceptor, 2 is donor, 3 is acceptor, 4 is acceptor - ✔✔C. 1 is acceptor, 2 is donor,
3 is acceptor, 4 is donor
✔✔Which of the following statements are correct regarding the relationship of pH and
pKa
1. When pH < pKa then the [A−]/[HA] ratio is greater than 1 and [A−] > [HA]
2. When pH < pKa then the [A−]/[HA] ratio is less than 1 and [HA] > [A−]
3. When pKa > pH then the [A−]/[HA] ratio is less than 1 and [A−] > [HA]
4. When pH < pKa then the [HA−]/[A] ratio is less than 1 and [HA−] > [A]
5. When pH > pKa then the [A−]/[HA] ratio is greater than 1 and [A−] > [HA]
6. When pH < pKa then the [A−]/[HA] ratio is less than 1 and [A−] > [HA]
A. 3,4,and5
B. 2,4,and6
C. 1and3
D. 2and5
E. None are correct - ✔✔D. 2and5
2. When pH < pKa then the [A−]/[HA] ratio is less than 1 and [HA] > [A−]
5. When pH > pKa then the [A−]/[HA] ratio is greater than 1 and [A−] > [HA]
✔✔What mediates the binding of histone proteins to DNA?
A. hydrophilic interactions
B. London dispersion forces
C. ionic interactions
D. hydrophobic interactions
,E. covalent bonds - ✔✔C. ionic interactions
✔✔Use the titration curve for acetic acid shown to the right to answer the three
questions and then choose the letter with all three correct answers.
(1) what is the most abundant ionic species at the point in the curve labeled A?
(2) what is the correct chemical term for the point on the curve labeled B?
(3) what is the most abundant ionic species at the point in the curve labeled C?
A. (1) CH3COO- (2) pK2 (3) CH3COOH
B. (1) CH3COOH (2) pKa (3) CH3COO-
C. (1) CH3COOH (2) pKeq (3) CH3COO-
D. (1) CH3COOH (2) pKd (3) CH3COO-
E. (1) CH3COO- (2) pKa (3) CH3COOH - ✔✔B. (1) CH3COOH (2) pKa (3) CH3COO-
✔✔Calculate the energy charge in a cultured cancer cell line found to have the following
adenylate concentrations: 1.25 mM ATP, 0.35 mM ADP, and 0.12 mM AMP. Is this too
high, too low, or normal?
A. 0.42 normal
B. 0.83 normal
C. 1.00 too high
D. 0.83 too low
E. 0.50 too low - ✔✔B. 0.83 normal
✔✔What would happen if DNA contained uracil instead of thymine as the adenine base
pair?
A. Naturally occurring uracil bases would not be distinguishable from cytosine
deamination events.
B. All of the uracil-adenine base pairs would be converted to guanine-cytosine base
pairs after replication.
C. Cytosine deamination would produce thymine, which would then form a hydrogen
bond with adenine.
D. All of the uracil-adenine base pairs would be converted to thymine-adenine base
pairs after replication.
E. Base-mediated phosphodiester cleavage would occur at uracil bases and rapidly
degrade the DNA. - ✔✔A. Naturally occurring uracil bases would not be distinguishable
from cytosine deamination events.
✔✔Which three amino acids are most likely be found in the core of a soluble and
globular protein?
A. 3, 5, 8
B. 2, 5, 6
C. 1, 4, 8
D. 2, 4, 6
E. 2, 4, 8 - ✔✔C. 1, 4, 8
VALINE, PHENYLALANINE, LEUCINE
, ALL HYDROPHOBIC
✔✔Which amino acid is (a) most unlikely to be in an alpha helix (b) most likely to be in a
beta turn?
A. (a) 7 (b) 9
B. (a) 3 (b) 4
C. (a) 5 (b) 6
D. (a) 2 (b) 7
E. (a) 6 (b) 8 - ✔✔A. (a) 7 (b) 9
PROLINE, GLYCINE
✔✔The R group charged at (a) pH 12.0 (b) charged at pH 3.0 (c) phosphorylated (d)
hydrophilic
A. (a) 2 (b) 3 (c) 5 (d) 6
B. (a) 3 (b) 2 (c) 6 (d) 5
C. (a) 2 (b) 6 (c) 5 (d) 3
D. (a) 3 (b) 2 (c) 5 (d) 6
E. (a) 1 (b) 3 (c) 5 (d) 7 - ✔✔D. (a) 3 (b) 2 (c) 5 (d) 6
ASPARTATE = charged @ ph 12,
LYSINE charged @ pH 3.0,
THREONINE phosphorylated,
GLUTAMINE hydrophilic
✔✔Which of the of 4 amino acids in the box to the right are most likely to be on the
surface of a water soluble protein?
A. Glu, Thr, Phe, Arg
B. Cys, Thr, Ser, Phe
C. Ala, Ile, Cys, Val
D. Ser, Thr, Asn, Gln
E. Phe, Trp, Tyr, His - ✔✔D. Ser, Thr, Asn, Gln
✔✔Does hydrogen bonding between base pairs account for the overall stability of the
DNA helix?
A. Yes, because guanine-cytosine base pairs have 3 hydrogen bonds and adenine-
thymine base pairs have two hydrogen bonds, so for every two base pairs of G-C and
A-T there are five hydrogen bonds.
B. No, because in high ionic strength solutions the number of hydrogen bonds between
bases is greater than the number of hydrogen bonds in pure water, and therefore helix
stability is actually due to Na+ ions.
C. Yes, because the length of hydrogen bonds between bases within the DNA helix is
shorter than the length of hydrogen bonds between the bases and water, so hydrogen
bonding does explain helix stability.
D. No, because hydrogen bonding between bases in the DNA helix is replaced by
hydrogen bonding with water in single strand DNA, therefore hydrogen bonding is
insufficient to explain why DNA helix is stable.
ANSWERS GRADED A+
✔✔What is the net reaction (1+2) shown below (???) andwhat is the ∆Gº' (???) for this
net reaction?
(1) NH4+ + Glutamate <-> Glutamine ∆Gº' = +14.2kJ/mol
(2) ATP <-> ADP + Pi ∆Gº' =-30.5 kJ/mol
(1 + 2) ????? <-> ??????? ∆Gº' = ????kJ/mol
A.ATP + Glutamate + NH4+ <-> Glutamine + ADP + Pi ∆Gº' = -16.3 kJ/mol
B.Glutamine + NH4+ <-> Glutamate + ATP ∆Gº' = -14.2 kJ/mol
C.NH4++ Glutamate + ADP + Pi <->Glutamine + ATP ∆Gº' = -30.5 kJ/mol
D.ATP + Glutamate + NH4+ <->Glutamine + ADP + Pi ∆Gº' = -44.7 kJ/mol
E.None of these answers are correct - ✔✔A.ATP + Glutamate + NH4+ <-> Glutamine +
ADP + Pi ∆Gº' = -16.3 kJ/mol
✔✔Is the circled group/atom a hydrogen bond donor or a hydrogen bond acceptor?
A. 1 is acceptor, 2 is acceptor, 3 is donor, 4 is donor
B. 1 is donor, 2 is acceptor, 3 is donor, 4 is acceptor
C. 1 is acceptor, 2 is donor, 3 is acceptor, 4 is donor
D. 1 is donor, 2 is donor, 3 is acceptor, 4 is donor
E. 1 is acceptor, 2 is donor, 3 is acceptor, 4 is acceptor - ✔✔C. 1 is acceptor, 2 is donor,
3 is acceptor, 4 is donor
✔✔Which of the following statements are correct regarding the relationship of pH and
pKa
1. When pH < pKa then the [A−]/[HA] ratio is greater than 1 and [A−] > [HA]
2. When pH < pKa then the [A−]/[HA] ratio is less than 1 and [HA] > [A−]
3. When pKa > pH then the [A−]/[HA] ratio is less than 1 and [A−] > [HA]
4. When pH < pKa then the [HA−]/[A] ratio is less than 1 and [HA−] > [A]
5. When pH > pKa then the [A−]/[HA] ratio is greater than 1 and [A−] > [HA]
6. When pH < pKa then the [A−]/[HA] ratio is less than 1 and [A−] > [HA]
A. 3,4,and5
B. 2,4,and6
C. 1and3
D. 2and5
E. None are correct - ✔✔D. 2and5
2. When pH < pKa then the [A−]/[HA] ratio is less than 1 and [HA] > [A−]
5. When pH > pKa then the [A−]/[HA] ratio is greater than 1 and [A−] > [HA]
✔✔What mediates the binding of histone proteins to DNA?
A. hydrophilic interactions
B. London dispersion forces
C. ionic interactions
D. hydrophobic interactions
,E. covalent bonds - ✔✔C. ionic interactions
✔✔Use the titration curve for acetic acid shown to the right to answer the three
questions and then choose the letter with all three correct answers.
(1) what is the most abundant ionic species at the point in the curve labeled A?
(2) what is the correct chemical term for the point on the curve labeled B?
(3) what is the most abundant ionic species at the point in the curve labeled C?
A. (1) CH3COO- (2) pK2 (3) CH3COOH
B. (1) CH3COOH (2) pKa (3) CH3COO-
C. (1) CH3COOH (2) pKeq (3) CH3COO-
D. (1) CH3COOH (2) pKd (3) CH3COO-
E. (1) CH3COO- (2) pKa (3) CH3COOH - ✔✔B. (1) CH3COOH (2) pKa (3) CH3COO-
✔✔Calculate the energy charge in a cultured cancer cell line found to have the following
adenylate concentrations: 1.25 mM ATP, 0.35 mM ADP, and 0.12 mM AMP. Is this too
high, too low, or normal?
A. 0.42 normal
B. 0.83 normal
C. 1.00 too high
D. 0.83 too low
E. 0.50 too low - ✔✔B. 0.83 normal
✔✔What would happen if DNA contained uracil instead of thymine as the adenine base
pair?
A. Naturally occurring uracil bases would not be distinguishable from cytosine
deamination events.
B. All of the uracil-adenine base pairs would be converted to guanine-cytosine base
pairs after replication.
C. Cytosine deamination would produce thymine, which would then form a hydrogen
bond with adenine.
D. All of the uracil-adenine base pairs would be converted to thymine-adenine base
pairs after replication.
E. Base-mediated phosphodiester cleavage would occur at uracil bases and rapidly
degrade the DNA. - ✔✔A. Naturally occurring uracil bases would not be distinguishable
from cytosine deamination events.
✔✔Which three amino acids are most likely be found in the core of a soluble and
globular protein?
A. 3, 5, 8
B. 2, 5, 6
C. 1, 4, 8
D. 2, 4, 6
E. 2, 4, 8 - ✔✔C. 1, 4, 8
VALINE, PHENYLALANINE, LEUCINE
, ALL HYDROPHOBIC
✔✔Which amino acid is (a) most unlikely to be in an alpha helix (b) most likely to be in a
beta turn?
A. (a) 7 (b) 9
B. (a) 3 (b) 4
C. (a) 5 (b) 6
D. (a) 2 (b) 7
E. (a) 6 (b) 8 - ✔✔A. (a) 7 (b) 9
PROLINE, GLYCINE
✔✔The R group charged at (a) pH 12.0 (b) charged at pH 3.0 (c) phosphorylated (d)
hydrophilic
A. (a) 2 (b) 3 (c) 5 (d) 6
B. (a) 3 (b) 2 (c) 6 (d) 5
C. (a) 2 (b) 6 (c) 5 (d) 3
D. (a) 3 (b) 2 (c) 5 (d) 6
E. (a) 1 (b) 3 (c) 5 (d) 7 - ✔✔D. (a) 3 (b) 2 (c) 5 (d) 6
ASPARTATE = charged @ ph 12,
LYSINE charged @ pH 3.0,
THREONINE phosphorylated,
GLUTAMINE hydrophilic
✔✔Which of the of 4 amino acids in the box to the right are most likely to be on the
surface of a water soluble protein?
A. Glu, Thr, Phe, Arg
B. Cys, Thr, Ser, Phe
C. Ala, Ile, Cys, Val
D. Ser, Thr, Asn, Gln
E. Phe, Trp, Tyr, His - ✔✔D. Ser, Thr, Asn, Gln
✔✔Does hydrogen bonding between base pairs account for the overall stability of the
DNA helix?
A. Yes, because guanine-cytosine base pairs have 3 hydrogen bonds and adenine-
thymine base pairs have two hydrogen bonds, so for every two base pairs of G-C and
A-T there are five hydrogen bonds.
B. No, because in high ionic strength solutions the number of hydrogen bonds between
bases is greater than the number of hydrogen bonds in pure water, and therefore helix
stability is actually due to Na+ ions.
C. Yes, because the length of hydrogen bonds between bases within the DNA helix is
shorter than the length of hydrogen bonds between the bases and water, so hydrogen
bonding does explain helix stability.
D. No, because hydrogen bonding between bases in the DNA helix is replaced by
hydrogen bonding with water in single strand DNA, therefore hydrogen bonding is
insufficient to explain why DNA helix is stable.
