BCH 361 CH 2 EXAM QUESTIONS
WITH ALL CORRECT ANSWERS
The van der Waals contact distance between two participating atoms is usually in the
range of angstroms.
a) 0.5 to 0.8
b) 2 to 5
a) 1 to 3
d) 4 to 6
e) 3 to 4 - Answer-e
In an electrostatic interaction, the strength of the bond is:
a) proportional to the charges on the two interacting atoms.
b) proportional to the dielectric constant of the medium.
c) inversely proportional to the distance between the two atoms.
d) Both the first and third answers are correct. - Answer-d
Within the helical structure of DNA, the bases are held together by , which are
relatively bonds.
a) hydrogen bonds; weak
b) ionic interactions; weak
c)covalent bonds; weak
d) ionic interactions; strong
e) hydrogen bonds; strong - Answer-a
What might be an effect if DNA nucleotide bases in a double helix were held together by
covalent bonds rather than hydrogen bonds?
a) Purified helices would require higher temperatures to melt apart the two DNA strands
b) The helix would be more stable.
c) Replication of DNA, which requires separation of the two strands, would require a
larger input of energy.
d) All of the above - Answer-d
Electrostatic interactions between two ions bearing single opposite charges separated
by 3 angstroms in water would have an energy that is when compared with the
energy between the same two ions separated by the same distance in a nonpolar
solvent.
a) more negative
b) more negative by a factor equal to the difference in the dielectric constants of the
water and the nonpolar solvent
c) equal
, d) more positive by a factor equal to the difference in the dielectric constants of the
water and the nonpolar solvent
e) more positive - Answer-e
Under appropriate conditions, protein folding proceeds:
a) amphipathically.
b) due to the hydrophobic effect.
c) spontaneously.
d) both amphipathically and due to the hydrophobic effect.
e) both spontaneously and due to the hydrophobic effect - Answer-e
You have a mixture of proteins with the following pKa's. Which of the statements below
is TRUE?
Protein X pKa = 2
Protein Y pKa = 6
Protein Z pKa = 10
a) At a pH of 6, protein Y will be 50% protonated and 50% deprotonated.
b) At a pH of 8, protein Y will be more protonated than protein Z.
c) At a pH of 6, the solution of protein X will contain more hydrogen ions than the
solution of protein Z. - Answer-a
Nonpolar solute molecules are driven together in water not primarily because they have
a high affinity for each other, but because, when they do associate, they release water
molecules. This association is called the . - Answer-Hydrophobic Effect
Which of the following has the lowest Ka?
a) bicarbonate
b) carbonic acid
c) dihydrogen phosphate
d) phosphoric acid
e) acetic acid - Answer-a
Which of the following is dependent on Brownian motion?
a) signal molecules diffusing from site of origin to site of effect
b) an enzyme finding a substrate
c) exchange of metabolites
d) All - Answer-d
WITH ALL CORRECT ANSWERS
The van der Waals contact distance between two participating atoms is usually in the
range of angstroms.
a) 0.5 to 0.8
b) 2 to 5
a) 1 to 3
d) 4 to 6
e) 3 to 4 - Answer-e
In an electrostatic interaction, the strength of the bond is:
a) proportional to the charges on the two interacting atoms.
b) proportional to the dielectric constant of the medium.
c) inversely proportional to the distance between the two atoms.
d) Both the first and third answers are correct. - Answer-d
Within the helical structure of DNA, the bases are held together by , which are
relatively bonds.
a) hydrogen bonds; weak
b) ionic interactions; weak
c)covalent bonds; weak
d) ionic interactions; strong
e) hydrogen bonds; strong - Answer-a
What might be an effect if DNA nucleotide bases in a double helix were held together by
covalent bonds rather than hydrogen bonds?
a) Purified helices would require higher temperatures to melt apart the two DNA strands
b) The helix would be more stable.
c) Replication of DNA, which requires separation of the two strands, would require a
larger input of energy.
d) All of the above - Answer-d
Electrostatic interactions between two ions bearing single opposite charges separated
by 3 angstroms in water would have an energy that is when compared with the
energy between the same two ions separated by the same distance in a nonpolar
solvent.
a) more negative
b) more negative by a factor equal to the difference in the dielectric constants of the
water and the nonpolar solvent
c) equal
, d) more positive by a factor equal to the difference in the dielectric constants of the
water and the nonpolar solvent
e) more positive - Answer-e
Under appropriate conditions, protein folding proceeds:
a) amphipathically.
b) due to the hydrophobic effect.
c) spontaneously.
d) both amphipathically and due to the hydrophobic effect.
e) both spontaneously and due to the hydrophobic effect - Answer-e
You have a mixture of proteins with the following pKa's. Which of the statements below
is TRUE?
Protein X pKa = 2
Protein Y pKa = 6
Protein Z pKa = 10
a) At a pH of 6, protein Y will be 50% protonated and 50% deprotonated.
b) At a pH of 8, protein Y will be more protonated than protein Z.
c) At a pH of 6, the solution of protein X will contain more hydrogen ions than the
solution of protein Z. - Answer-a
Nonpolar solute molecules are driven together in water not primarily because they have
a high affinity for each other, but because, when they do associate, they release water
molecules. This association is called the . - Answer-Hydrophobic Effect
Which of the following has the lowest Ka?
a) bicarbonate
b) carbonic acid
c) dihydrogen phosphate
d) phosphoric acid
e) acetic acid - Answer-a
Which of the following is dependent on Brownian motion?
a) signal molecules diffusing from site of origin to site of effect
b) an enzyme finding a substrate
c) exchange of metabolites
d) All - Answer-d
