QUIZ #1 - Introduction, Water, pH, buffers, Amino Acids, Proteins, Separation Techniques
1.
Which of the following colligative properties of water is responsible for cardiomyocyte lysis resulting
during an MI?
a. Dielectric
b. Osmotic
c. Freezing point depression
d. Polarity
e. Hydrophobic
2.
A muscle fiber that is using glycolysis as its main energy source:
a. Will use creatine phosphokinase as its next reserve energy source
b. Is metabolizing under anaerobic conditions
c. Is generating 1/5th as much energy as it would if it were also using the TCA cycle
d. Will produce high concentrations of acetyl-CoA which inhibit glycolysis
3.
A patient=s coronary arteries normally have a diameter of 20, but years of consuming ABig Macs@ has
helped form a thrombus that reduced the diameter to 14. Approximately how much has the blood flow
through the vessel decreased?
a. A. No change in blood flow
b. 30%
c. 55%
d. 75%
e. 95%
4.
Which of the following would be used to separate amino acids on the basis of polarity?
a. Bulk phase chromatography
b. Thin layer chromatography
c. Ion exhange chromatography
d. Free boundary electrophoresis
e. Both A and B
f. Both C and D
5.
Which of the following techniques may be used to separate proteins on the basis of size?
a. Dialysis
b. Gel exclusion chromatography
c. SDS-PAGE electrophoresis
d. Ultracentrifugation
e. All of the above
6.
A 65 year old woman comes into the ER complaining of severe chest discomfort. She reports that the
pain began about 4 hrs earlier. Which of the following would you expect to rise most rapidly during the
next 24 hours?
a. The H4 isozyme of lactate dehydrogenase
b. The MB isozyme of creatine phosphokinase
c. The pH
d. All of the above
7. If one were to double BOTH the radius AND length of a vessel, by what factor would the blood flow
increase?
a. 2X
b. 4X
c. 8X
d. 16X
e. 100X
8. During prolonged ischemia, a myocyte depends solely upon glycolysis for its ATP production. Under
these conditions, which of the following would be expected to inhibit glycolysis?
a. Decreased pH
b. Increased ATP
c. Increased AMP
d. Complete oxygen deprivation
e. Accumulation of intracellular glucose
9. Base on the data, what is the molar absorptivity (in mmol) of the solution (where the light path = 1 cm)?
Concentration (mmol) Observed absorption
0.015
0.022
0.043
0.067
0.0081
0.012
0.023
0.036
a. 2.3
b. 1.7
c. 0.54
d. 0.05
10. Which of the following amino acids would be eluted first from a cation exchange chromatography
column when the pH = 7?
a. Arginine
b. Aspartic acid
c. Lysine
d. Both A and C would co-elute together before aspartic acid
e. All three amino acids would adhere to the resin and not elute at pH = 7
11. Which of the following describes the Henderson-Hasselbalch equation where HA is the acid?
a. pH = pK + log [A-]/[HA]
b. pH = pK - log [A-]/[HA]
c. pH = pK + log [HA]/[A-]
d. pk = pH + log [A-]/[HA]
12. What is the normal bicarbonate to CO2 ratio ([HCO3-] / 0.03 x pCO2) at physiological pH?
a. 2:1
b. 10:1
c. 20:1
d. 40:1
e. 24:40
13. Which of the following is NOT true about the pI of a tri-protic amino acid?
a. When the pH = pI, the amino acid has no net charge
b. When the pH = pI, the amino acid will not migrate in an electric field
c. When the pH = pI, the amino acid is at its greatest buffering capacity
d. When the pH = pI, the pK of each ionizable group is unchanged
14. Concerning buffers, which of the following is true?
a. Strong acid and bases are good buffers
b. Buffers cause dramatic pH changes
c. The -NH2 / -NH3+ pair is a good buffer near a pH of 2.5
d. Buffers may be a mixture of a weak acid and its conjugate base
e. Buffers are Agood@ only if they buffer at or near physiological pH
15. Under which of the following conditions does the pH = pK?
a. [A-] / [HA] = 1
b. HA is a strong acid
c. [conjugate base] = [weak acid]
d. pH = pK + log10
e. Both 1) and 3) are correct
16. During respiratory acidosis, which of the following does NOT occur?
a. Physiological pH decreases
b. The pCO2 in the blood increases
c. Blood levels of H2CO3 increase at a faster rate than HCO3d. The kidney excretes extra bicarbonate into the urine
e. The respiratory rate increases
17. If the pCO2 of the blood was 60mmHg, what would the [HCO3-] need to be in order to maintain pH at
7.4?
a. 18
b. 24
c. 32
d. 36
e. 40
18. At what pH is the alpha-carboxyl group of an amino acid approximately half deprotonated?
a. 2.5
b. 4.5
c. 6.0
d. 9.5
e. 10.5
19. What is the approximate charge on the following polypeptide at physiological pH?
Pro - Leu - Asp - Asn - Lys - Arg - Trp - Val
a. Negative
b. Positive
c. Neutral
20. The pK of carbonic acid is:
a. Greater than physiological pH
b. Equal to physiological pH
c. Lower than physiological pH
d. Depends upon the pH
21. Which of the following amino acid(s) may undergo(es) post-translation modification?
a. Serine
b. Tyrosine
c. Proline
d. Cysteine
e. All of the above
22. Which of the following amino acids does NOT possess an ionizable R group?
a. Lys
b. Arg
c. Ile
d. Asp
e. Tyr
23. Which of the following amino acids is both polar and essential?
a. Phenylalanine
b. Isoleucine
c. Tyrosine
d. Alanine
e. Lysine
24. What is the net charge on aliphatic amino acids at pH =8?
a. "0" (net zero charge)
b. Slightly negative
c. Slightly positive
d. +2
25. How many fragments will result from the treatment of chymotrypsin on the following protein?
H2N - lys-phe-ala-thr-trp-arg-his-pro-val-ser-tyr-gln-COOH
a. 0
b. 1
c. 2
d. 3
e. 4
26. A four amino acid peptide has the following residues:
tyr, phe, arg and met
Cleavage with CNBr OR with chymotrypsin both yield two fragments of unequal size. What is the
sequence of the peptide?
a. arg-met-phe-tyr
b. tyr-phe-arg-met
c. met-arg-phe-tyr
d. met-tyr-phe-arg
e. phe-tyr-met-arg
27. In a protein, what level of structure most directly determines the function of that protein?
a. Primary
b. Secondary
c. Tertiary
d. Allosterism
e. S-S disulfide bond formations
28. What is the principal determinant of the primary structure of a protein?
a. VanDer Waals forces
b. Hydrogen bonding
c. Ionic interactions
d. Hydrophobic forces
e. Genetic forces
29. What is the driving force determining the tertiary structure of a protein?
a. VanDer Waals forces
b. Hydrogen bonding
c. Ionic interactions
d. Hydrophobic forces
e. Genetic forces
30. Which amino acid is both aliphatic and branched?
a. Arginine
b. Methionine
c. Tyrosine
d. Leucine
e. Serine
31. A molecule rotates plane polarized light to the left (ie., is levorotatory). Which of the following is the
proper designation for this type of molecule?
a. D
b. d
c. L
d. l