Final Exam Review Quiz

Question 1

During the final exam period, many students choose to imbibe a large amount of energy drink to stay alert and focused. Many energy drinks may display a nutritional label similar to the one shown below (imagine):

With the nutrients provided in the above energy drink, match the nutrients to their likely metabolic functions.

NUTRIENTS:
1. Sugar e.g. glucose
2. Riboflavin B2
3. Niacin B3
4. Sodium
5. Carnitine
6. Glucuronolactone

FUNCTION
- Precursor for making NAD+, which plays a key role in alpha-ketoglutarate dehydrogenase.
- Plays a role in translocating acyl CoA.
- Used as fuel for aerobic respiration
- Precursor for making FAD, which plays a key role in the pyruvate dehydrogenase complex.
- Is essential in uptaking glucose in the intestinal cells.
- Can be easily used in the pentose phosphate pathway.

Answer 1

1. Sugar e.g. glucose - Used as fuel for aerobic respiration
2. Riboflavin B2 - Precursor for making FAD, which plays a key role in the pyruvate dehydrogenase complex.
3. Niacin B3 - Precursor for making NAD+, which plays a key role in alpha-ketoglutarate dehydrogenase.
4. Sodium - Is essential in uptaking glucose in the intestinal cells.
5. Carnitine - Plays a role in translocating acyl CoA.
6. Glucuronolactone - Can be easily used in the pentose phosphate pathway.

Question 2

One of the nutrients commonly found in the energy drink is taurine. Based on the structure of taurine, speculate which one of the 20 common amino acids can give rise to taurine?

a) Cysteine
b) Lysine
c) Methionine
d) Alanine

Answer 2

a) Cysteine

Question 3

Caffeine, another common ingredient found in the energy drinks, non-covalent inhibits an enzyme that degrades cAMP.

Therefore, drinking energy drinks containing caffeine should promote breakdown of stored energy, such as glycogen and fat.

a) True
b) False

Answer 3

a) True

Question 4

In sickle cell anemia Glu 6 (non polar) of the beta subunit is replaced with valine (polar), which causes the hemoglobin to aggregate. The underlying cause of this aggregation could be due to:

a) a newly formed salt bridge between the alpha and beta subunits
b) steric clash of the larger valine side chain
c) hydrogen bonding between valine and water
d) hydrogen bonding between the side chain of valine 6 and the alpha subunit (?)
e) the hydrophobic effect

Answer 4

e) the hydrophobic effect

Question 5

When hemoglobin folds _______

a) secondary structure will form first.
b) hydrophobic residues will point towards solvent.
c) the alpha and beta subunits will associate before folding.
d) tertiary structure is the last type of structure to form.
e) the protein will sample all possible orientations

Answer 5

a) secondary structure will form first.

Question 6

Hemoglobin requires ______.

a) a prosthetic group to function
b) a reducing environment to function
c) a cofactor to function
d) cleavage by proteolytic enzymes to function
e) a magnesium ion for function

Answer 6

a) a prosthetic group to function

Question 7

By size exclusion chromatography you estimate the molecular weight of hemoglobin to be 64 kDa. If you denatured hemoglobin and analyzed it by SDS-PAGE, what molecular weight would you expect the bands to appear at? Hint: Recall that hemoglobin is a heterotetramer (made of 4 subunits).

a) Approximately 128 kDa
b) Approximately 64 kDa
c) Approximately 32 kDa
d) Approximately 16 kDa
e) Approximately 8 kDa

Answer 7

d) Approximately 16 kDa

Question 8

If hemoglobin is mutated such that it cannot enter the T state, you may expect that _______

a) hemoglobin would become even better at transporting oxygen to the lungs.
b) hemoglobin would adopt a hyperbolic oxygen binding curve.
c) allosteric effectors such as BPG would have an enhanced effect.
d) there would be no change to the oxygen binding characteristics of hemoglobin.
e) its affinity for oxygen would decrease.

Answer 8

b) hemoglobin would adopt a hyperbolic oxygen binding curve.

Question 9

The following peptide was derived from hydrolyzing hemoglobin: Gln-Gln-Lys.

What is the approximate isoelectric point of this peptide?

a) 10.5
b) 5.75
c) 9.75
d) 9
e) 3.5

Answer 9

c) 9.75

Question 10

What volume of a 6 mg/mL stock solution of hemoglobin is required to create 12 mL of a 2 µg/mL solution of hemoglobin?

a) 4 µL
b) 40 µL
c) 400 µL
d) 4 mL
e) 40 mL
f) 400 mL
g) 4 L
h) none of the above

Answer 10

a) 4 µL

..or 0.004 mL