ACS Biochemistry Practice Final, FGCU, Beharry, Coticone Exam | Actual
Questions and Answers Latest Updated 2024/2025 (Graded A+)
1. A weak acid, HA, has a pKa of 4.11.
a) At pH 7.11, what will the ratio of conjugate base to acid be? (Henderson-Hasselbach equation:
pH=pKa + log [A-]/[HA])
b) Based on answer to "a," is there more HA or A- at that pH?
c) At pH 2.11, what will the ratio of conjugate base to acid be?
d) Based on answer to "c," is there more HA or A- at that pH?
e) At pH 4.11, what will the ratio of conjugate base to acid be?
f) Fill in the blank: if pH is greater than the pKa of a weak acid, there will be ___ A- relative to HA. If the
pH is less that the pKa of a weak acid, there will be __ A- relative to HA. If the pH=pKa, there will be ___
of A- and HA. - ✔✔a) 7.11=4.11+log[x]
3=log[x]
1000=x
b) A-
c) 2.11=4.11+log[x]
-2=log[x]
0.01=x
d) HA
e) 1
f) more; less; the same amount
2.
a) Which amino acids would be charged at pH 7?
b) which amino acids from "a" would be negatively charged?
c) which amino acids from "a" would be positively charged? - ✔✔a) Asp, Glu, Arg, His, Lys
b) Asp, Glu
c) Arg, His, Lys
, 3. Which of the following sequences is most likely to be in the interior core of a globular protein? Why?
a) ITFWLI
b) IKFGVA
c) DKYPGE
d) MPCDNA - ✔✔A; because no charged amino acids and highest % of nonpolar
4. How are beta sheets stabilized in proteins? - ✔✔Hydrogen bonding between peptide backbone
groups?
5. Compare fibroud proteins such as keratin and globular proteins:
a) Water solubility
b) flexible secondary structure
c) highly repetitive primary structure
d) size and ability to associate into larger structures - ✔✔a) fibrous: insoluble
globular: soluble
b) fibrous: no
globular: yes
c) fibrous: yes
globular: not necessarily
d) fibrous: elongated structrue; two alpha keratin polypeptides, each of which form an alpha helix,
twisting around each other to form a left-handed coil
globular: varies
6. A mixture of proteins was separate on a gel filtration column using a pH 7 buffer. Using the info
below, put them in order of elution (first to last)
Protein A: MW 27kDa, pI 2
Protein B: MW 144kDa, pI 11
Protein C: MW 43kDa, pI 9 - ✔✔b>c>a
Questions and Answers Latest Updated 2024/2025 (Graded A+)
1. A weak acid, HA, has a pKa of 4.11.
a) At pH 7.11, what will the ratio of conjugate base to acid be? (Henderson-Hasselbach equation:
pH=pKa + log [A-]/[HA])
b) Based on answer to "a," is there more HA or A- at that pH?
c) At pH 2.11, what will the ratio of conjugate base to acid be?
d) Based on answer to "c," is there more HA or A- at that pH?
e) At pH 4.11, what will the ratio of conjugate base to acid be?
f) Fill in the blank: if pH is greater than the pKa of a weak acid, there will be ___ A- relative to HA. If the
pH is less that the pKa of a weak acid, there will be __ A- relative to HA. If the pH=pKa, there will be ___
of A- and HA. - ✔✔a) 7.11=4.11+log[x]
3=log[x]
1000=x
b) A-
c) 2.11=4.11+log[x]
-2=log[x]
0.01=x
d) HA
e) 1
f) more; less; the same amount
2.
a) Which amino acids would be charged at pH 7?
b) which amino acids from "a" would be negatively charged?
c) which amino acids from "a" would be positively charged? - ✔✔a) Asp, Glu, Arg, His, Lys
b) Asp, Glu
c) Arg, His, Lys
, 3. Which of the following sequences is most likely to be in the interior core of a globular protein? Why?
a) ITFWLI
b) IKFGVA
c) DKYPGE
d) MPCDNA - ✔✔A; because no charged amino acids and highest % of nonpolar
4. How are beta sheets stabilized in proteins? - ✔✔Hydrogen bonding between peptide backbone
groups?
5. Compare fibroud proteins such as keratin and globular proteins:
a) Water solubility
b) flexible secondary structure
c) highly repetitive primary structure
d) size and ability to associate into larger structures - ✔✔a) fibrous: insoluble
globular: soluble
b) fibrous: no
globular: yes
c) fibrous: yes
globular: not necessarily
d) fibrous: elongated structrue; two alpha keratin polypeptides, each of which form an alpha helix,
twisting around each other to form a left-handed coil
globular: varies
6. A mixture of proteins was separate on a gel filtration column using a pH 7 buffer. Using the info
below, put them in order of elution (first to last)
Protein A: MW 27kDa, pI 2
Protein B: MW 144kDa, pI 11
Protein C: MW 43kDa, pI 9 - ✔✔b>c>a
