Glycolysis

Question 1

Glycolysis serves two major functions in the cell:

Answer 1

1) Generates ATP

2) Provides building blocks for biosynthesis (generates precursors for a.a synthesis and fatty acid synthesis)

Question 2

Stage 1 of glycolysis

Answer 2

The trapping (of glucose in the cell) and preparation phase
- No ATP is generated
Aim: generate two phosphorylated 3-C fragments
From glucose to glyceraldehyde 3-phosphate

Question 3

Glucose enters the cell through specific transport proteins and is phosphorylated to form glucose 6-phosphate by ATP and hexokinase

Answer 3

1) g-6-p cannot pass through the membrane to the extracellular side
2) The addition of the phosphoryl group facilitates the metabolism of glucose to phosphorylated 3-C compounds with high phosphoryl-transfer potential

Question 4

Isomerization of g-6-p to f-6-p

Answer 4

• Catalyzed by phosphoglucose isomerase -> changes position -> aldehyde into ketone in order to split into 2
• Conversion of aldose into ketose

Question 5

F-6-p is phosphorylated by ATP and PFK-1 to f-1,6-bp

Answer 5

phosphofructokinase (PFK-1): an allosteric enzyme key regulatory enzyme for glycolysis, phosphorylates f-6-p

Question 6

F-1,6-bp is cleavaged into 2 triose phosphates

Answer 6

By aldolase into dihydroxyacetone (DHAP) and glyceraldehyde 3-phosphate (GAP)

Question 7

Equilibrium favours dihydroxyacetone phosphate

Answer 7

Dihydroxyacetone phosphate will be turned into glyceraldehyde 3-phosphate. This rxn proceeds readily bc the subsequent rxns of glycolysis remove this product.

Question 8

Stage 2 of Glycolysis

Answer 8

The Payoff Phase

• 3C fragments are oxidized to pyruvate
• 2ATP is generated overall

Question 9

GAP to 1,3-bpglycerate

Answer 9

GAP dehydrogenase catalyzes this redox rxn, often transferring a hydride ion from a donor molecule to NAD+ or transferring a hydride ion from NADH to an acceptor molecule
1,3-BPG has high phosphoryl-transfer potent

Question 10

ATP is formed by phosphoryl transfer from 1,3-BPG

Answer 10

1,3-BPG transfers a phosphate group to ADP -> substrate-level phosphorylation

Question 11

3-phosphoglycerate to 2-phosphoglycerate

Answer 11

moves the location of the phosphate group for easier phosphorylation shortly

Question 12

Phosphoenolpyruvate to pyruvate

Answer 12

Another substrate-level phosphorylation occurs to ADP to make ATP bc phosphoenolpyruvate has high energy to transfer phosphoryl group