Glycolysis extra notes

Question 1

What is the net overall reaction of glycolysis?

Answer 1

Glucose + 2 NAD+ + 2 ADP + 2 Pi = 2 pyruvate + 2 NADH + 2 ATP

Question 2

Give two reasons for the spontaneity of glycolysis.

Answer 2

1. More products are formed

2. Oxidation reaction (Dehydrogenation) in reaction 6

Question 3

What are the three fates of glucose?

Answer 3

1. Excess glucose is stored as glycogen (Starch in plants)
2. Glucose is converted to pyruvate (catabolism for energy)
3. Pentose-phosphate pathway (glucose forcibly oxidized)

Question 4

What is pasteur’s effect. What is the reasoning behind it?

Answer 4

Pasteur’s effect is that aerobic growth of yeast requires less glucose than the anaerobic condition.
The reasoning behind it is that glycolysis has a low efficiency for making ATP whilst reducing pyruvate to acetyl COA produces more ATP.

Question 5

What is required for fermentation?

Answer 5

Pi

Question 6

Iodoacetate treatment causes accumulation of what?

Answer 6

Fructose-1,6-biphosphate

Question 7

What does fluoride treatment cause accumulation of?

Answer 7

2-phosphoglycerate and 3-PG

Question 8

What steps compose the preparatory stage, which the payoff stage.

Answer 8

1-5

6-10

Question 9

What is the importance of phosphorylated intermediates? Why is glucose phosphorylated in the first reaction?

Answer 9

1 - Possession of negative charge inhibits membrane diffusion
2 - Conservation of free energy in high energy phosphate bond
3. Facilitation of catalysis

Question 10

The tautomerization step from enol-pyruvate to keto-pyruvate supplies considerably more free energy than the phosphoryl group transfer step. True or False.

Answer 10

True

Question 11

What are the fates of pyruvate?

Answer 11

1 - Completely oxidized to CO2 under aerobic conditions
2 - Alcoholic fermentation - anaerobic
3 - Homolactic fermentation - anaerobic

Question 12

What is the oxidizing agent in homolactic fermentation?

Answer 12

Pyruvate

Question 13

What is the reducing agent in homolactic fermentation?

Answer 13

NADH

Question 14

What is vitamin B1?

Answer 14

Thiamine

Question 15

In reaction 6 of glycolysis, once NADH is replaced with NAD+, what does NAD+ do?

Answer 15

Attracts Pi from solvent.

Question 16

What are the two types of control for metabolic reactions?

Answer 16

1 - Substrate limited. Occurs when the concentration of reactants and products in the cell are near eqb. Availability of substrate decides the rate of reaction.

2 - Enzyme limited:
- concentration of products and reactants are far from eqb. Activity of enzyme decides rate of reaction. Control the flux of glycolysis as a whole.

Question 17

What are the three steps in glycolysis that have enzymes which regulate the flux of glycolysis?

Answer 17

Hexokinase, PFK-1, PK

Question 18

Which enzymes are involved in the regulation of PFK-1?

Answer 18

Adnylate kinase and Fructose-1,6-biphosphatase.

Question 19

What does adnylate kinase do?

Answer 19

Readily equilibrates 2 ADP molecules into 1 ATP and 1 AMP molecule. The AMP then activates PFK-1 further.

Question 20

What does FBPase do?

Answer 20

Catalyzes the conversion of FBP to F6P thus, reverting the PFK reaction.