©Themoon EXAM SOLUTIONS
25/11/2024 13:32PM
BIOC 3021 Practice Exam 1 Questions and
Answers
A buffer solution is made from a weak acid, HA (pKa 6.0) and its conjugate base A-. What is
the ratio of the base A- to the acid HA at pH 5.0? - Answers✓✓pH = pKa + log[A-]/[HA]
5 = 6 + log[A-]/[HA]
-1 = log [A-]/[HA]
10^-1 = ratio
raio = 0.1
Which of these elements is the least common in organic compounds within living cells?
a) C
b) F
c) S
d) N - Answers✓✓B- fluoride
If the hydrogen ion
, ©Themoon EXAM SOLUTIONS
25/11/2024 13:32PM
concentration of the blood increases ten-fold, how much does the pH change? - Answers✓✓pH
decreases one unit
If the pH changes from 7.0 to 6.0 which amino acid R-group is the most affected?
(Hint: The most affected R-group is the one with a pK the closest to pH 7.0)
a) Lysine
b)Aspartate
c) Glutamate
d) Histidine
e) Arginine - Answers✓✓Histidine: pK=6
lysine(pK=10.5), arginine (pK=12.5)
aspartate (pK=3.9), glutamate (pK=4.3)
Which amino acid is essentially incompatible with alpha helix and beta sheet formation? -
Answers✓✓Proline
Which type of interaction is NOT stabilized by hydrogen bonds - Answers✓✓water and a
nonpolar R-group
*nonpolar groups are hydrophobic*
In proteins the R-groups of the polar but uncharged amino acids, serine and glutamine generally
can form _______ bonds with each other. - Answers✓✓HYDROGEN
25/11/2024 13:32PM
BIOC 3021 Practice Exam 1 Questions and
Answers
A buffer solution is made from a weak acid, HA (pKa 6.0) and its conjugate base A-. What is
the ratio of the base A- to the acid HA at pH 5.0? - Answers✓✓pH = pKa + log[A-]/[HA]
5 = 6 + log[A-]/[HA]
-1 = log [A-]/[HA]
10^-1 = ratio
raio = 0.1
Which of these elements is the least common in organic compounds within living cells?
a) C
b) F
c) S
d) N - Answers✓✓B- fluoride
If the hydrogen ion
, ©Themoon EXAM SOLUTIONS
25/11/2024 13:32PM
concentration of the blood increases ten-fold, how much does the pH change? - Answers✓✓pH
decreases one unit
If the pH changes from 7.0 to 6.0 which amino acid R-group is the most affected?
(Hint: The most affected R-group is the one with a pK the closest to pH 7.0)
a) Lysine
b)Aspartate
c) Glutamate
d) Histidine
e) Arginine - Answers✓✓Histidine: pK=6
lysine(pK=10.5), arginine (pK=12.5)
aspartate (pK=3.9), glutamate (pK=4.3)
Which amino acid is essentially incompatible with alpha helix and beta sheet formation? -
Answers✓✓Proline
Which type of interaction is NOT stabilized by hydrogen bonds - Answers✓✓water and a
nonpolar R-group
*nonpolar groups are hydrophobic*
In proteins the R-groups of the polar but uncharged amino acids, serine and glutamine generally
can form _______ bonds with each other. - Answers✓✓HYDROGEN
