Metabolism

Question 1

What is gluconeogenesis

Answer 1

The production of glucose from non sugar precursors eg. lactate, amino acid and pyruvate.

Question 2

Gluconeogenesis is essentially the opposite…..

Why is it not the exact reverse of …..

Answer 2

Glycolysis

As glycolysis has three irreversible steps

Question 3

What are the irreversible steps of glycolysis (ALSO THE CONTROL POINTS)

Their enzymes

Answer 3

1) Glucose> glucose-6-phosphate
2) Fructose-6-phosphate> fructose 1,6 biphosphate
3) Triose phosphate> pyruvate

1) hexokinase
2) phosphofructokinase
3) pyruvate kinase

Question 4

What is produced at the end of glycolysis

Answer 4

Net gain of
2ATP
2NADH
2 pyruvate

(Both produced when triose phosphate is cleaved to pyruvate)

Question 5

What do the three control points of glycolysis control and their inhibitors

Answer 5

Hexokinase- substrate entry (glucose-6-phosphate)

Phosphofructokinase- rate of flow (inhibited by ATP) (frucotse-6-phosphate>fructose-1,6-bisphosphate)

Pyruvate kinase- product exit (inhibited by ATP)

Question 6

run down of how pyruvate is converted into acetyl coa (4)

Answer 6

Via oxidative phosphorylation. (2CoA)
Mediated by pyruvate dehydrogenase
NADH + CO2 released

(Bare in mine glycolysis produces 2 pyruvate therefore 2NADH + 2CO2 are produced )

Question 7

How does pyruvate enter the mitochondrial matrix

Answer 7

Passive diffusion into inter-membrane space if mitochondria

Facilitated diffusion into mitochondrial matrix

Question 8

TCA cycle control points (and what step number they are)

Answer 8

All inhibited by NADH and ATP + the following

Pyruvate> acetyl CoA. pyruv dehyd Inhibited by acetyl CoA

(1) Acetyl CoA> citrate. citrate synthase inhibited by citrate & succinyl CoA
(3) Isocitrate > alpha ketoglutarate. (isocitrate dehydrogenase)
(4) Alpha ketoglutarate> succinyl CoA. alpha ketoglutanate dehydrogenase Inhibited by succinyl CoA

Question 9

Net yield of a molecule of glucose and what steps they come from

Answer 9

Gylcolysis - 2 ATP, 2NADH

x2 Pyruvate> 2 acetyl CoA - 2NADH, 2H, 2CO2

TCA cycle (x2) = 6NADH, 2FADH, 2GTP,4CO2

Total= 
32 ATP
10 NADH
2 FADH
6 CO2
10 H+
2 GTP

Question 10

Example of carrier molcule that transports fatty acids through inner mitochondrial membrane

Answer 10

Carnitine