Metabolism 3

Question 1

What are the 3 stages of metabolism?

Answer 1

1. Digestion
2. Cellular Metabolism 1
3. Cellular Metabolism 2

Question 2

Reaction 1 of Glycolysis

Answer 2

1. Glucose —–> Glucose-6-phosphate

Enzyme: hexokinase (1 ATP used)

Question 3

Reaction 2 of Glycolysis

Answer 3

2. Glucose-6-phosphate ———-> Fructose-6-phosphate

Enzyme: Phosphoglucose isomerase

Question 4

Reaction 3 of Glycolysis

Answer 4

3. Fructose-6-phosphate ——-> Fructose-1,6-biphosphate

Enzyme: Phosphofructokinase

(1 ATP used)

Question 5

Reaction 4 of Glycolysis

Answer 5

4. Fructose-1,6-biphosphate ——-> Glyceraldehyde-3-phosphate (G3P) +dihydroxyacetone phosphate

Enzyme: Aldolase

Question 6

Reaction 5 of Glycolysis

Answer 6

5. Dihydroxyacetone phosphate ——> G3P

Enzyme: Triose phosphate isomerase

Question 7

Reaction 6 of Glycolysis

Answer 7

6. G3P ——> 1,3-biphosphoglycerate

Enzyme: G3P dehydrogenase

2x NADH generated (one for each G3P molecule)

Question 8

Reaction 7 of Glycolysis

Answer 8

7. 1,3-biphosphoglycerate —–> 3-phosphoglycerate

Enzyme: phosphoglycerate kinase

2x ATP produced

Question 9

Reaction 8 of Glycolysis

Answer 9

8. 3-phosphoglycerate ——-> 2-phosphoglycerate

Enzyme: phosphoglycerate mutase

Question 10

Reaction 9 of Glycolysis

Answer 10

9. 2-phosphoglycerate ——> phosphoenolpyruvate

Enzyme: Enolase

Dehydration type of reaction

Question 11

Reaction 10 of Glycolysis

Answer 11

10. Phosphoenolpyruvate ——> pyruvate

Enzyme: Pyruvate kinase

2x ATP generated

Question 12

At the half way stage of glycolysis, what are the stats?

Answer 12

> 2 ATP used
2 moles of G3P produced
no ATP produced

Question 13

What is substrate level phosphorylation?

Answer 13

ATP production via direct transfer of a high energy phosphate group from an immediate substrate in biochemical pathway to ADP.

Glycolysis is an example of substrate level phosphorylation.

Question 14

What is oxidative phosphorylation?

Answer 14

ATP production using energy derived from transfer of e- in an e- transport system.

Question 15

What are the 3 possible fates of Pyruvate?

Answer 15

1. Alcoholic fermentation
2. Lactate production
3. Acetyl CoA generation

Question 16

Explain alcoholic fermentation of pyruvate.

Answer 16

1. Pyruvate to acetaldehyde (ethanal)

Enzyme: pyruvate decarboxylase

(H+ —-> CO2)

2. Acetaldehyde —-> Ethanol

Enzyme: alcohol dehydrogenase

(NADH + H+ —-> NAD+)

Question 17

Explain lactate generation.

Answer 17

Anaerobic process.

In conditions of oxygen deprivation, lactate production serves to regenerate NAD+ (essentially for glycolysis to continue)

Pyruvate ——–> Lactate

Enzyme: Lactate dehydrogenase

Question 18

What molecule is a phosphate reservoir to phosphorylate ADP?

Answer 18

Creatine phosphate.

Muscle damage causes Creatine phosphate to leak into bloodstream

Creatine phosphate <===> creatine + ATP

Question 19

Where does acetyl-CoA production occur?

Answer 19

In the mitochondria

Question 20

Explain Acetyl-CoA generation.

Answer 20

Pyruvate + HS-CoA ——> Acetyl-CoA + CO2

Enzyme: Pyruvate Dehydrogenase Complex

NAD+ —-> NADH !!

Question 21

What does the Pyruvate Dehydrogenase complex consist of?

Answer 21

3 Enzymes

5 co-factors

(some prosthetics are a PERMANENT part of the complex)

Question 22

What are the 5 steps of the Pyruvate Dehydrogenase Complex?

Answer 22

1. Decarboxylation of pyruvate. Gives hydroxyethyl TPP.
2. Hydroxyethyl TPP oxidised and transferred to lipoamide. Gives acetyl-lipoamide.
3. Acetyl group transferred to CoA. Gives Acetyl CoA.
4. Oxidised lipoamide regenerated. Gives FADH2.
5. Oxidised FAD regenerated. Gives NADH

Question 23

Compare ATP generation in anaerobic and aerobic respiration.

Answer 23

Anaerobic = 2 ATP

Aerobic = 38 ATP

Question 24

Which reaction in glycolysis produces NADH?

Answer 24

Reaction 6.

Question 25

Which reactions in glycolysis produce ATP?

Answer 25

Reactions 7 and 10