Lecture 24

Question 1

What is glyolysis?

Answer 1

The splitting of glucose molecules to form pyruvate

Question 2

What does glycolysis provide?

Answer 2

The net gain of 2ATP

Question 3

What are the two stages of glycolysis?

Answer 3

Energy investment and energy payoff

Question 4

What is energy investment?

Answer 4

Spending 2ATP to add 2 phosphates onto glucose in two stages - activation of glucose (x2)

Question 5

What is activation of glucose?

Answer 5

Getting the molecule into a form so energy can be captured, adding phosphates (x2)

Question 6

Is the activation of glucose energetically favourable or unfavourable?

Answer 6

Energetically unfavourable, +ve gibbs energy

Question 7

How can an energetically unfavourable reaction made favourable?

Answer 7

By reaction coupling

Question 8

What is the activation of glucose coupled with?

Answer 8

ATP hydrolysis

Question 9

Is the conversion of G-6-P to F-6-P energetically favourable or unfavourable?

Answer 9

Energetically unfavourable, however, because it is in the middle of the pathway, it is driven forward to completion.

Question 10

What happens at the end of the energy investment phase?

Answer 10

The aldolase reaction

Question 11

What are the two key reactions for ATP synthesis?

Answer 11

ATP synthesis and redox reactions using coenzymes

Question 12

What is the reaction of ATP synthesis?

Answer 12

ADP + Pi -> ATP

Question 13

What type of phosphorylation is ATP synthesis?

Answer 13

Substrate-level phosphorylation, direct. Energy comes straight from substrate

Question 14

What type of phosphorylation is a redox reaction?

Answer 14

Oxidative phosphorylation, indirect through reduced co-enzymes

Question 15

What is substrate-level phosphorylation

Answer 15

The direct use of energy from a substrate molecule to drive the synthesis of ATP

Question 16

How is energy released through substrate-level phosphorylation?

Answer 16

Through cleaving a high energy phosphate bond

Question 17

What is the problem with a SLP and net energy gain?

Answer 17

1 ATP must be spent to create the phosphate bond and 1ATP is made when the bond is cleaved, no net energy gain

Question 18

How is the problem of net energy gain fixed?

Answer 18

Through redox reactions using coenzymes

Question 19

What is a redox reaction?

Answer 19

Fuel molecules get oxidised a co enzyme gets reduced

Question 20

What are the key coenzymes?

Answer 20

NAD and FAD

Question 21

What is NAD?

Answer 21

Nicotinamide adenine dinucleotide, derived from niacin (V-B3)

Question 22

What does NAD undergo?

Answer 22

A two-electron reduction

Question 23

What is a reducing equivalent?

Answer 23

H atom with 2H+ and 2e-

Question 24

Why is 3PG rearranged?

Answer 24

To get the molecule into a form that enables the following reactions to occur

Question 25

What does the second substrate level phosphorylation provide?

Answer 25

Pyruvate from PEP using pyruvate kinase and an ATP molecule

Question 26

What is the overall reaction for glycolysis?

Answer 26

Glucose + 2NAD+ + 2ADP + 2Pi -> 2 pyruvate + 2NADH + 2ATP + 2H+

Question 27

What is arsenic poisioning of glycolysis?

Answer 27

Arsenate (AsO4³⁻) replaces phosphate (PO4³⁻) in the reaction from G-3-P, forming 1-arseno-3-phosphoglycerate instead of 1,3-BPG. This releases energy as heat instead of producing ATP (no net loss or gain)

Question 28

What are the fates of pyruvate?

Answer 28

Aerobic oxidation and anaerobic glycolysis

Question 29

What is an aerobic reaction?

Answer 29

One with plentyful oxygen

Question 30

What is an anaerobic reaction?

Answer 30

One with limited/low oxygen

Question 31

What occurs during aerobic oxidation of pyruvate?

Answer 31

Pyruvate undergoes pyruvate dehydrogenation into acetyl in the mitochondrial matrix which is then bound to CoA to further be metabolized in the CAC.

Question 32

What is CoA?

Answer 32

Coenzyme A (CoA) is derived from pantothenic acid (vitamin B5) and is not a carrier of electrons, therefore cannot preform a redox reaction.

Question 33

What are the two forms of CoA?

Answer 33

Free coenzyme A: CoASH and Acyl group attached: Acyl-CoA

Question 34

What happens in anareobic glycolysis of pyruvate?

Answer 34

Pyruvate is converted to lactate. Lactate causes muscle fatigue. After this, glycolysis can continue to generate ATP

Question 35

Where does anaerobic glycolysis of pyruvate occur?

Answer 35

In the red blood cells and muscle