Name: ________________________
Exam 1: BCHM 2700
Given: pH = pKa + log([A-]/[HA]) for ax2+bx+c = 0, x = (-b±√(b2-4ac))/2a
pH = -log[H ]
+ at 25 C: Kw = 1.0 x 10-14
o ΔG = ΔH - TΔS
𝒀
Hill equation: log𝟏−𝒀 = nlog[L]- logKd
[𝑳]
For noncooperative binding: θ = Y = [𝑳]+𝑲 and Kd = p50
𝒅
[𝑳]𝒏
For cooperative binding: θ = Y = [𝑳]𝒏 +𝑲 and Kd = (p50)n
𝒅
Multiple choice: circle the best answer (2 pts each).
1. Prokaryotes include which of the 4. Calculate the [H+] in a solution with
following domains in the biological pOH = 4.8.
classification system? a. 6.3 x 10-10 M [OH-] = +10-pOH- = 1.585 x 10-5
b. 1.6 x 10-5 M K w = [H ][OH ]
a. archaea [H+] = Kw/[OH-] =
c. 4.8 M (1.0 x 10-14)/(1.585 x 10-5)
b. bacteria d. 9.2 M
c. eukarya e. 1.6 x 109 M
d. both archaea and bacteria
e. both archaea and eukarya 5. The neutral pH of water at 0 oC is 7.48.
What is the ion product constant of
2. Which of the following compounds water (Kw) at 0 oC?
would have the lowest melting point? a. 1.91 x 1012 The neutral point is when [OH-] = [H+]
b. 6.14 x 10 -7 [H+] = 10-pH = 10-7.48
+ - -7.48 -7.48
c. 5.25 x 10-13 Kw = [H ][OH ] = 10 x 10
d. 1.00 x 10-14
All have a net dipole, but e. 1.10 x 10-15
a) has the least surface
area, resulting in fewer
instantaneous dipoles. 6. Mechanical hyperventilation forces
faster breathing and is a useful
treatment for ______ as it _____ .
a. acidosis; lowers pCO2 in the blood
e. all of the above compounds would b. alkalosis; lowers pCO2 in the
have the same melting point. blood
c. acidosis; raises pCO2 in the blood
3. What is the conjugate base of d. alkalosis; raises HCO3- in the
H2CrO4? blood
a. CrO42- e. halitosis; raises pCO2 in the blood
The conjugate base has Hyperventilation forces faster removal of CO2 from
b. HCrO4- one fewer proton. the blood. This forces H+ and HCO3- to combine to
c. H2CrO3 make more H2O and CO2 to restore equilibrium. Less
d. H3CrO4+ H+ increases pH to help with acidosis.
e. OH-
, 7. Tris is a weak monoprotic acid. If 0.22 11. Which of the following statements
mol of Tris base and 0.050 mol of Tris about β-sheets is true?
acid mixed in 0.50 L of solution results a. β-sheets are stabilized by
in a pH of 8.94. What is the pKa of hydrogen bonding between
Tris? peptide backbone functional
a. 7.46 groups.
b. 8.30 pH = pKa + log([A-]/[HA])
pKa = pH - log([A-]/[HA])
b. β-sheets may be formed from two
c. 9.14 = 8.94 - log(0.22 mol/0.50 L)/(0.050 mol/0.50 L) or more parallel β-strands.
d. 9.58 pKa = 8.30 c. β-sheets may be formed from two
e. 10.42 or more anti-parallel β-strands.
d. β-sheets are elements of regular
8. The quaternary structure of a protein secondary structure.
is: e. all of the above
a. the overall structure of multiple
interacting subunits. 12. What is the estimated net charge of
b. the structure of an entire the peptide sequence cysteine-
polypeptide. tyrosine-arginine-serine at a
c. the local conformations of a pH of 2.0?
polypeptide segment. Group Typical pKa
d. the sequence of amino acids. Terminal α-carboxyl 3.1 0
e. a right-handed double helix. group
Aspartic 4.1
9. In Anfinsen’s protein refolding acid/glutamic acid
experiments, RNase A was denatured Histidine 6.0
with urea and its four disulfide bonds Terminal α-amino 8.0 +1
were broken by β–mercaptoethanol. group
Which of the following refolding Cysteine 8.3 0
procedures would recover the most Tyrosine 10.0 0
RNase A activity? Removing urea allows the
Lysine 10.4
hydrophobic effect to
a. dialysis, then oxidation drive initial folding and Arginine 12.5 +1
b. dialysis, then reduction positioning of the Cys a. -1
c. oxidation, then dialysis residues. Oxidation then b. 0
makes the correct
d. reduction, then dialysis disulfide bonds. c. +1
e. additional urea, then reduction d. +2
e. +3
10. Individual α-helices in keratin
associate with one another due to 13. Aggregates of the infectious (PrPSc)
_________ to form a coiled-coil dimer. form of prion proteins:
a. disulfide bonds The 1st and 4th a. induce disulfide crosslinks in
b. lysine crosslinks residues of each
PrPc.
c. ionic interactions heptad repeat are
generally b. phosphorylate PrPc.
d. hydrogen bonding c. cleave PrPc.
hydrophobic and
e. the hydrophobic effectpromote dimer d. induce a change in folding of PrPc.
formation. e. lack β-sheets.
Exam 1: BCHM 2700
Given: pH = pKa + log([A-]/[HA]) for ax2+bx+c = 0, x = (-b±√(b2-4ac))/2a
pH = -log[H ]
+ at 25 C: Kw = 1.0 x 10-14
o ΔG = ΔH - TΔS
𝒀
Hill equation: log𝟏−𝒀 = nlog[L]- logKd
[𝑳]
For noncooperative binding: θ = Y = [𝑳]+𝑲 and Kd = p50
𝒅
[𝑳]𝒏
For cooperative binding: θ = Y = [𝑳]𝒏 +𝑲 and Kd = (p50)n
𝒅
Multiple choice: circle the best answer (2 pts each).
1. Prokaryotes include which of the 4. Calculate the [H+] in a solution with
following domains in the biological pOH = 4.8.
classification system? a. 6.3 x 10-10 M [OH-] = +10-pOH- = 1.585 x 10-5
b. 1.6 x 10-5 M K w = [H ][OH ]
a. archaea [H+] = Kw/[OH-] =
c. 4.8 M (1.0 x 10-14)/(1.585 x 10-5)
b. bacteria d. 9.2 M
c. eukarya e. 1.6 x 109 M
d. both archaea and bacteria
e. both archaea and eukarya 5. The neutral pH of water at 0 oC is 7.48.
What is the ion product constant of
2. Which of the following compounds water (Kw) at 0 oC?
would have the lowest melting point? a. 1.91 x 1012 The neutral point is when [OH-] = [H+]
b. 6.14 x 10 -7 [H+] = 10-pH = 10-7.48
+ - -7.48 -7.48
c. 5.25 x 10-13 Kw = [H ][OH ] = 10 x 10
d. 1.00 x 10-14
All have a net dipole, but e. 1.10 x 10-15
a) has the least surface
area, resulting in fewer
instantaneous dipoles. 6. Mechanical hyperventilation forces
faster breathing and is a useful
treatment for ______ as it _____ .
a. acidosis; lowers pCO2 in the blood
e. all of the above compounds would b. alkalosis; lowers pCO2 in the
have the same melting point. blood
c. acidosis; raises pCO2 in the blood
3. What is the conjugate base of d. alkalosis; raises HCO3- in the
H2CrO4? blood
a. CrO42- e. halitosis; raises pCO2 in the blood
The conjugate base has Hyperventilation forces faster removal of CO2 from
b. HCrO4- one fewer proton. the blood. This forces H+ and HCO3- to combine to
c. H2CrO3 make more H2O and CO2 to restore equilibrium. Less
d. H3CrO4+ H+ increases pH to help with acidosis.
e. OH-
, 7. Tris is a weak monoprotic acid. If 0.22 11. Which of the following statements
mol of Tris base and 0.050 mol of Tris about β-sheets is true?
acid mixed in 0.50 L of solution results a. β-sheets are stabilized by
in a pH of 8.94. What is the pKa of hydrogen bonding between
Tris? peptide backbone functional
a. 7.46 groups.
b. 8.30 pH = pKa + log([A-]/[HA])
pKa = pH - log([A-]/[HA])
b. β-sheets may be formed from two
c. 9.14 = 8.94 - log(0.22 mol/0.50 L)/(0.050 mol/0.50 L) or more parallel β-strands.
d. 9.58 pKa = 8.30 c. β-sheets may be formed from two
e. 10.42 or more anti-parallel β-strands.
d. β-sheets are elements of regular
8. The quaternary structure of a protein secondary structure.
is: e. all of the above
a. the overall structure of multiple
interacting subunits. 12. What is the estimated net charge of
b. the structure of an entire the peptide sequence cysteine-
polypeptide. tyrosine-arginine-serine at a
c. the local conformations of a pH of 2.0?
polypeptide segment. Group Typical pKa
d. the sequence of amino acids. Terminal α-carboxyl 3.1 0
e. a right-handed double helix. group
Aspartic 4.1
9. In Anfinsen’s protein refolding acid/glutamic acid
experiments, RNase A was denatured Histidine 6.0
with urea and its four disulfide bonds Terminal α-amino 8.0 +1
were broken by β–mercaptoethanol. group
Which of the following refolding Cysteine 8.3 0
procedures would recover the most Tyrosine 10.0 0
RNase A activity? Removing urea allows the
Lysine 10.4
hydrophobic effect to
a. dialysis, then oxidation drive initial folding and Arginine 12.5 +1
b. dialysis, then reduction positioning of the Cys a. -1
c. oxidation, then dialysis residues. Oxidation then b. 0
makes the correct
d. reduction, then dialysis disulfide bonds. c. +1
e. additional urea, then reduction d. +2
e. +3
10. Individual α-helices in keratin
associate with one another due to 13. Aggregates of the infectious (PrPSc)
_________ to form a coiled-coil dimer. form of prion proteins:
a. disulfide bonds The 1st and 4th a. induce disulfide crosslinks in
b. lysine crosslinks residues of each
PrPc.
c. ionic interactions heptad repeat are
generally b. phosphorylate PrPc.
d. hydrogen bonding c. cleave PrPc.
hydrophobic and
e. the hydrophobic effectpromote dimer d. induce a change in folding of PrPc.
formation. e. lack β-sheets.
