Glycolysis

Question 1

Step 1

Answer 1

Hexokinase

• energy cost
• phosphorylation of glucose on Carbon 6, keeps it in the cytosol and thus transporters cannot recognise molecule, thus REGULATED step

Glucose —> glucose-6- phosphate

• can be stored as glycogen, or used in synthesis of fatty acids, nucleic acids etc
• moves into pentose phosphate pathway

Question 2

Step 2

Answer 2

Glucose -6-phosphate —-> fructose-6-phosphate

Reversible and unregulated
Enzyme is phosphohexose isomerase

Question 3

Step 3

Answer 3

Phosphofructokinase (PFK-1)
Irreversible, coupled with ATP hydrolysis
First committed step to glycolysis because glucose-6-phosphate can come from glycogen
Allosteric regulation of PFK

Fructose-6-phosphate —> fructose 1,6 biphosphate

Question 4

Step 4

Answer 4

Aldolase

Cleavage favoured since triose phosphates are quickly removed.

Question 5

Step 5

Answer 5

Triose phosphate isomerase

Glyceraldehyde (GAP) degraded further by hydrolysis

Question 6

Step 6

Answer 6

Glyceraldehyde 3-phosphate dehydrogenase

Production of NADH as electron carrier

Question 7

Step 7

Answer 7

Phosphoglycerate kinase

Produces ATP to allow step 6 to occur

Question 8

Step 8

Answer 8

Phosphoglycerate murase

Transfer of phosphoryl group

Question 9

Step 9

Answer 9

Enolase
Formation of high energy phosphate From PEP
- difference in distribution of energy accounts for this formation

Question 10

Step 10

Answer 10

Pyruvate kinase
Phosphoryl transfer from PEP to PPP
Irreversible and highly regulated
Produced ATP

Question 11

Summary

Answer 11

10 steps
3 irreversible / highly regulated steps: 1,3 and 10
- key enzymes hexokinase, PFK, pyruvate kinase
- 2 NADH molecules produced (step 6)
- 2 ATP modules produced (7 and 10)