Key Enzymes

Question 0

What enzyme is involved in step 3 of glycolysis?

Answer 0

Phosphofructokinase

Question 1

What enzymes can be involved in stage 1 of glycolysis?

Answer 1

Usually hexokinase, glucokinase in liver at high glucose concentration

Question 2

How is hexokinase regulated?

Answer 2

Product inhibition- glucose 6 phosphate

Question 3

What enzyme is involved in step 10 of glycolysis?

Answer 3

Pyruvate kinase

Question 4

How is step 10 regulated?

Answer 4

Activated by high insulin:glucagon which causes dephosphorylation

Question 5

Lactase enzyme deficiency?

Answer 5

Deficiency causes lactose intolerance, diarrhoea and stomach ache due to bacteria in gut feeding on undigested lactose

Question 6

Galactosaemia???

Answer 6

Galactokinase or galactose 1 p uridyl transferase deficiency.
Transferase is more severe and common. Both cause cataracts but transferase also causes liver, kidney and brain damage due to build up of Glucose 1 P

Question 7

Glucose 6 phosphate dehydrogenase??

Answer 7

Converts g-6-p to ribose sugar along while converting NADP to NADPH, deficiency causes disulphide bridges to form causing Heinz bodies, leading to anaemia, jaundice and lethargy, as well as cataracts.

Question 8

Pyruvate dehydrogenase???

Answer 8

Converts pyruvate to acetyl CoA, irreversible due to loss of CO2, so acetyl CoA can’t be converted to pyruvate and used in gluconeogenesis. Activated by dephosphorylation promoted by insulin, dependent on energy needs of cell

Question 9

What is the structure of pyruvate dehydrogenase and why is this important?

Answer 9

It is a multi enzyme complex, allowing a complex reaction to occur in a controlled manner. Requires several cofactors derived from vitamin b so function sensitive to vitamin b deficiency.

Question 10

How is Phosphofructokinase regulated? What activates/inhibits it?

Answer 10

Allosteric regulation- activated by ADP, inhibited by ATP

Hormonal regulation- activated by insulin, inhibited by glucagon