QUESTION 1: Cell fractions and buffers

(a) What factors determines the forces that a particle experience during centrifugation?

(b) Name the techniques usually employed to obtain cell free extracts/"brake cells open".

(c) Indicate how mitochondria can be isolated by differential centrifugation.

(d) Why is it important to know the pKa of a buffer?

(e) Write the structures of the two components of an acetate buffer and name them.

QUESTION 2: Amino acids. protein, proteins, spectrophotometry and gel filtration.

(a) Write the structure of eysteine showing all the groups bound to the central carbon atom.

(b) Calculate the pl of glycine. (pKa value of α-COOH = 2.2 and pKa α-NH₂ = 9.50).

(c) Using a figure explain the mechanisms by which ion exchange can separate ions.

(d) Draw the structure of the dipeptide glycyl glycine.

(e) Define standard curve as used in spectrophotometry.

(f) Name two gels that can be used in gel filtration work.

QUESTION 3: Coenzymes and Vitamins

(a) Define the term coenzymes.

(b) Describe how NADH₂ formation can he followed spectrophotometrically.

(c) What general symptoms are associated with a deficiency of vitamin B₃?

(d) Write the chemical reaction catalysed by glutamyl decarboxylase and indicate the coenzymes involved in the process.

QUESTION 4: Enzyme kinetics

(a) Define the term enzyme activity and give the units thereof.

(b) If Vo = K₃[ES], explain why V_max = K₃[ES]_max

(c) Define aliosteric control of enzyme activity.

(d) Show the general reaction scheme for irreversible inhibition.

(e) Define and also discuss the importance of the turnover number of an enzyme.