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Medical Biochemistry Question Paper

Medical Biochemistry

Course:Bachelor Of Medicine

Institution: Kenyatta University question papers

Exam Year:2009

KENYATTA UNIVERSITY
UNIVERSITY EXAMINATIONS 2008/2009
SECOND SEMESTER EXAMINATION FOR THE DEGREE OF BACHELOR
OF MEDICINE
HMB 103:
MEDICAL BIOCHEMISTRY

DATE: Thursday, 10th September, 2009
TIME: 9.00 a.m. – 12.00 p.m.
------------------------------------------------------------------------------------------------------------
INSTRUCTIONS:
Section A: Answer all the three Questions (5 Marks each)
1. Fill in the information missing in the following Table
Disease Enzyme Lipid Clinical symptoms
accumulating
Tay-Sach’s Hexosaminidase
A

Fabry’s Alpha-
galactosidase

Krabbe’s
Beta- galactisidase

Gaucher’s
ß- glucosidase

Niemann- PiCK
sphingomyelinase

2. The ability of glycolysis to provide ATP in the absence of oxygen is especially
important because it allows ___________ to perform at very high levels when
oxygen supply is insufficient and because it allows tissues to survive
________________. However, __________ muscle, which is adapted for
aerobic performance, has relatively low glycolytic activity and poor survival
under conditions of __________. Diseases in which enzymes of glycolysis

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(eg, pyruvate kinase) are deficient are mainly seen as __________________
or, if the defect affects skeletal muscle (eg, phosphofructokinase), as
___________________ In fast-growing cancer cells, glycolysis proceeds at a
higher rate than is required by the citric acid cycle, forming large amounts of
___________, which is reduced to _______________ and exported. This
produces a relatively ______________ local environment in the tumor which
may have implications for _______________.

3. Most proteins are active only within a narrow pH range, 5-9. This is a result of
the effects of pH on a combination of factors:
(a)………………………………………………………………………………
(b)………………………………………………………………………………
(c)………………………………………………………………………………
(d)………………………………………………………………………………

Section B: Answer all the three Questions (5 Marks each)
1. Define the terms
i.
Hypoxia
ii.
Gluconeogenesis
iii.
Glycogenesis
iv.
Hypoglycemia
v.
Isozymes
2. Explain how the kinetic parameters KM and Vmax (Kcat) can be used to decide
whether an enzymatic reaction occurs through steady state or equilibrium
mechanism.
3. a. What are the non-steroidal anti-inflammatory drugs (NS AIDS)?
b. Briefly explain the mechanism of acetyl-salicylic acid (aspirin) and its
significance
Section C: Answer all the three Questions (10 Marks each)

1. Discuss Cori and Glucose-Alanine cycles
2. Explain the mode of action of the following anti-cholesterol therapies.
a. Anion exchange resins.
b. Competitive inhibitors of HMG-CoA reductase.
3. Describe how the irreversible glycolytic reactions are bypassed in
gluconeogenesis.

2

Section D: Multiple Choice Questions (5 Marks each)
Instructions:
Answer True or False.
1. The following statements refer to lipoproteins. Indicates which is true or false
A. High density lipoproteins (HDL) are involved in the transport of
cholesterol from peripheral tissues to the liver.
B. High level of HDL- cholesterol is detrimental to health.
C. The major protein moieties of HDL are apoliproteins A-I and A-II.
D. HDL appears to the antitherogenic
E. None of the above.

2. The following metabolic processes may be active in the fasting states. Which
ones are true or false?
A. Activating cAMP-dependent hormone sensitive lipase in adipose
tissue.
B. Lipolysis of triglycerols of chylomicrons by lipoproteins lipases in
capillaries.
C. Activation of Acetyl-coA carbaxylase in liver.
D. Phosphorylation of glycerol by glycerol kinase adipose
E. None of the above
3. In the fed state, when fatty acids are being synthesized in liver they cannot
immediately undergo beta oxidation. Which of the statements below is true or
false?
A. cAMP and fatty acyl coA depress the activity of acetyl CoA
carboxylase.
B. They are used in esterification pathway.
C. Fatty acyl- coA inhibits mitochondrial citrate synthesis
D. Insulin leads to increased uptake of glucose into cells and on an
increased rate of glycolysis.
E. None of the above.

4. In the control of fatty acid metabolism, which of the following statements are
true or false?
A. When fuel is abundant fatty acid oxidation is enhanced
B. High carbohydtrares intake causes increased fatty acid synthesis.
C. High carbohydrate causes decreased fatty acid synthesis.
D. Palmitoyl-coA has no effect on fatty acid synthesis.
E. None of the above.

5. The following are regulators of Pyruvate Dehydrogenase Multienzyme Complex
A) NADH
B) FADH2
C) Pyruvate
D) Glucose
E) Acetyl-CoA

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6. The following are substrates of gluconeogenesis
A. Alanine
B. Glycerol
C. Oxaloacetate
D. Succinate
E. 1,3-Bisphosphoglycerate

7. The following enzymes catalyze reactions in the preparatory phase of glycolysis
A. Aldolase
B. Enolase
C. Phosphoglycerate mutase
D. Hexokinase
E. Phosphohexose isomerase

8. The following hormones are positive effectors of Fructose-1,6-Bisphosphatase
A. Insulin
B. Glucagon
C. Epinephrine
D. Norepinephrine
E. Growth hormone

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Medical Biochemistry Question Paper

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