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Ich2140:Biochemistry Ii Question Paper

Ich2140:Biochemistry Ii

Course:Public Health

Institution: Meru University Of Science And Technology question papers

Exam Year:2010

1
a) State a biochemical and a physiological function of the following minerals.(5 Marks)
i. Calcium
ii. Phosphorous
iii. Potassium
b) The pyruvate dehydrogenase complex (PDH) is composed of three (3) enzymes.
(5 Marks)
i. Name the enzymes that make up the complex.
ii. Which vitamins are important cofactors/prosthetic groups for these enzymes?
Link the prosthetic group to the enzyme.
c) Calculate the standard free – energy change of the reaction catalyzed by the enzyme
phosphoglucomutase,
Glucose -1- phospate ? glucose -6-phosphate.
Given that, starting with 20mM Glucose -1-phosphate and no Glusoce -6-phosphate,
the final equilibrium, mixture at 25°?? and pH 7 contains 1.0mM Glucose-1-phosphate
and 19mM Glucose -6-phospate.
Does the reaction in the direction of Glucose -6-phosphate formation proceed with a
loss or gain of free energy? (R = 8.315J./mol.K (5 Marks)
d) i) Explain what hormones are. (2 Marks)
ii) State the functions of the following hormones. (3 Marks)
2
(i) Gastrin
(ii) Secretin
(iii)Cholecystokinin
e) Konberg and his colleagues incubated soluble extracts of E.Coli with a mixture
dATP, TTP, dGTP and GCTP all labeled with 32P in the ? -??h??????h?????? group. After
a time, the incubation mixture was treated with trichloroacetic acid which precipitates
the DNA but not the nucleotide precursors. The precipitate was collected and the
extent of precursor incorporation into DNA was determined from the amount of
radioactivity present in the precipitate. (5 Marks)
i. Explain if any of the four nucleotide precursors were omitted from the
incubation mixture, would radioactivity be found in the precipitate?
ii. Explain whether 32P would be incorporated into DNA if only dTTP were
labeled.
iii. Explain whether radioactivity would be found in the precipitate if 32?? labelled
the ?? - or ?? phosphate rather than the ? -??h??????h?????? of
deoxyrigonucleotides.
f) i) Explain what semiconservative replication of DNA is.
ii) Explain what okazaki fragments are.
iii) Mismatch repair moves replication errors by exercising the incorrect bases.
Explain how the cell distinguishes the newly synthesized strand from the correct
parental DNA strand to be preserved.
SECTION B
QUESTION TWO (20 MARKS)
Describe in details reactions of the glycolytic pathway.
QUESTION THREE (20 MARKS)
a) Draw the structures of the excretory forms of nitrogen; ammonium ion, urea and uric
acid.
b) Show the reactions for amino group catabolism in verbrate liver.
QUESTION FOUR (20 MARKS)
Describe the reactions of the Citric Acid cycle/TCA/ Krebs cycle.
QUESTION FIVE (20 MARKS)
Discuss the mechanisms of enzyme catalysis.

Ich2140:Biochemistry Ii Question Paper

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