carbohydrate metabolism

Question 1

name the 4 enzymes involved in a series of hydrolysis reactions in starch degradation

Answer 1

alpha-amylase = cleaves alpha 1,4 linkages internally (endo-hydrolase)
limit dextrinase = cleaves alpha 1,6 branch linkages
beta-amylase = releases maltose from the non-reducing end (exo-hydrolase)
maltase = hydrolyses maltose to glucose

Question 2

what happens to monosaccharides during glycolysis

Answer 2

monosaccharides are oxidised either aerobically or anaerobically

Question 3

how many reaction in glycolysis are irreversible

Answer 3

3

Question 4

which enzymes catalyse the 3 irreversible reactions of glycolysis

Answer 4

hexokinase
phosphofructokinase
pyruvate kinase

Question 5

the major control point in glycolyisis is the reaction catalysed by…

Answer 5

PFK

Question 6

what is PFK activity inhibited by

Answer 6

ATP

Question 7

what 2 sites on PFK does ATP bind on

Answer 7

catalytic site - phosphoryl transfer to fructose 6-P
allosteric site - different from active site

Question 8

what happens when PFK is inhibited

Answer 8

• accumulation of fructose 6-P + glucose 6-P
• inhibition of hexokinase (product inhibition)
• less glucose is phosphorylated to glucose 6-P
• lower rate of glucose entry into glycolysis