Glycolysis

Question 1

Glycolysis Background info

Answer 1

• Function: Obtain energy & intermediates for other pathways

Question 2

How is Glucose transported into cells?

Answer 2

• Glucose Transporters (GLUT1-GLUT5): Facilitated diffusion

- regulation by hormones: blood [sugar] linked to metabolic reactions

Question 3

Define glycolysis

Answer 3

‘Splitting Sugars’

• Catabolism of Glucose, yielding 2x Pyruvate

Question 4

State the ATP invested stages

Answer 4

Stage 1 + 2

From;
Glucose to Glyceralderhyde 3-phosphate (2 ATP consumed)

Question 5

Glucose + ___ –> Glucose-6-phosphate + ___

Answer 5

Glucose + ATP –> Glucose-6-phosphate + ADP

Question 6

Reaction 1

• Transfer of a ___ , from ATP to Glucose?
• Enzyme name?

Answer 6

1) Phosphate from ATP –> Glucose

- Hexokinase: Requires Mg2+-ATP complex (Mg essential for kinase activity)

Question 7

What happens to Hexokinase in the presence of Glucose?

Answer 7

• Glucose induces conformational change in hexokinase
• -> hexokinase migrates ATP close to Glucose’s 6thC

(ATP phosphate excludes H20 from active site)

Question 8

Reaction 2

• Conversion of __ to __ by ____ isomerase.
• Isomeration of an ___ to ___

Answer 8

2) Conversion of ‘Glc-6P’ to ‘Fru-6P’ by ‘phosphoglucose’ isomerase.
- Isomeration of an ‘aldose to ‘ketose’
- Reaction is reversible

Question 9

Reaction 3

Process of;
- Fruc-6P –> Fruc 1,6-biphosphate

Importance of;
- ‘Phosphofructokinase (PFK)

Answer 9

• Phosphorylation of Fruc-6P –> Fruc 1,6 biP

- PFK controls rate of glycolysis

Question 10

Reaction 4

• Cleavage of Fruc-1,6-biP to ___ & ___
• Which triose continues the glycolytic pathway?

Answer 10

Cleavage of Fruc-1,6-biP to;

• Glyceraldehyde-3-phosphate (GA3P)
• Dihydroxyacetone phosphate (DHAP)
• Only GA3P continues!

Question 11

Reaction 5

• Dihydroxyacetone phosphate (DHAP) is converted to __?
• Enzyme to catalyse this reaction?

Answer 11

• Dihydroxyacetone phosphate (DHAP) converted to Glyceraldehyde-3-phosphate (GA3P)
• Conversion by;
  Triose phosphate isomerase

Question 12

Reactions 1-5

• Yield ___?
• Consume __?
• Energy ___ phase?

Answer 12

• Yields 2x Glyceraldyhyde-3-phosphate
• Consumes 2x ATP
• Energy ‘Investment’ phase

Question 13

Reactions 6-10

• Generate __ ATP?
• Steps 6-10 repeated __ times?

Answer 13

4 ATP produced
- 2ATP per molecule (4 ATP)

Steps occur twice = 2x GA3P molecules.

Question 14

Reaction 6

• What happens to GA3P?
• Requiring what enzyme?

Answer 14

• GA3P is Oxidised & Phosphorylated to produce;
  1,3-biphosphoglycerate (1,3-bPG)
• Use of NAD+

Question 15

Reaction 7

- A Phosphate is ___ from 1,3-bPG
Substrate level phosphorylation

Answer 15

• Phosphate removal from 1,3-bPG to produce;
  3-phosphoglycerate (3-PG)
• First ATP generated!
  (2x molecules = 2ATP)

Question 16

Reaction 8

• 3-PG converted to ___?

Answer 16

• 3-PG converted to 2-phosphoglycerate

Phosphate group moved from the 3rd Carbon to the 2nd
- 3-PG –> 2-PG

Question 17

Reaction 9

2-PG is __ forming Phosphoglycerate

Answer 17

2-PG is dehydrated to Phosphoglycerate (PG)

• H20 is removed!

Question 18

Reaction 10

Phosphoglycerate (PG) is _____ , forming Pyruvate

(substrate level phosphorylation)

Answer 18

Phosphate is removed from Phosphoglycerate, forming;
- Pyruvate

• Second ATP generated!
  (2x molecules = 2ATP)

Question 19

Reactions 6-10

• 2x Glyceraldehyde-3-phosphate undergo __ , __ , __ , producing __
• Generating __ & __

Answer 19

2x Glyceraldehyde-3P undergo:
- Phosphorylation
- Oxidation
- Rearrangement
= Converted to: Pyruvate!

Generating:

• 2 ATP (4-2)
• 2 NADH

Question 20

Steps 1-10

• Does Glycolysis require Oxygen?
• Fate of Pyruvate from Glycolysis?

Answer 20

• Glycolysis occurs anaerobically!

- Pyruvate enters Citric Acid Cycle

Question 21

Fate of Pyruvate?

Answer 21

1) to Ethanol (Yeast)
2) to Lactate (in muscles: lack of O2)
3) Citric Acid Cycle