Energy generation: Second stage of glycolysis

Question 1

What is the second stage of glycolysis?

Answer 1

Fructose 1,6-bisphosphate —> Dihydroxyacetone + Glyceraldehyde 3-phosphate

Converted by aldolase

Reaction is freely reversible due to small -veΔG

Both 3-carbon sugars contain a phosphorus group needed for further metabolism

However, only glyceraldehyde 3-phosphate is needed for the rest of the steps of glycolysis

Question 2

What happens to the dihydroxyacetone?

Answer 2

Dihydroxyacetone —> Glyceraldehyde 3-phosphate by triose phosphate isomerase

Enzyme is the fastest known enzyme and rate of catalysis approach the theoretical limit set by diffusion in solution

Question 3

How is dihydroxyacetone phosphate linked to lipid catabolism and biosynthesis?

Answer 3

Glycerol can be converted to dihydroxyacetone phosphate

1) Glycerol L-glycerol 3-phosphate by glycerol kinase and ATP= PHOSPHORYLATED
2) L-Glycerol 3-phosphate —-> Dihydroxyacetone phosphate by glycerol phosphate dehydrogenase and NAD+ = OXIDISED
3) Dihydroxyacetone phosphate D-Glyceraldehyde 3-phosphate

Link: Glycerol kinase and glycerol phosphate dehydrogenase are involved in converting glycerol to dihydroacetone which can then be converted to Glyceraldehyde 3-phosphate = another way for glycerol to enter the pathway