Glycolysis Quiz

reaction #1 - Hexokinase Catalyzed Reaction

enzyme: hexokinase

purpose:

1. adds 1st phosphate group

2. traps glucose in the cell

glucose — > glucose 6-phosphate (G-6P)

reaction #2 - phosphoglucose isomerase catalyzed reaction (aldose into ketose)

enzyme: phosphoglucose isomerase

purpose:

1. move carbonyll group to ensure that each product of aldol cleavage (in rxn #4) contains 3 carbons (2,3-carbon molecules)

glucose 6-phosphate (G-6P) ——> fructose 6-phosphate (F-6P)

reaction #3 - phophofructokinas catalyzed reaction 

enzyme: phosphofructokinase (PFK)

purpose:

1. adds 2nd phosphate group, so both products in aldolase cleavage reaction have a phosphate group and are isomers of each other.

COMMITTED STEP

fructose 6-phosphate (F-6P) ——> fructose 1,6-bisphosphate (F-1,6BP)

reaction #4 - aldolase catalyzed reaction

enzyme: aldolase

purpose:

1. cleave a 6-carbon molecule between C3 & C4 into 2, rapidly convertible 3-carbon isomers

fructose 1,6-bisphosphate (F-1,6BP) ——> Dihydroxacetone phosphate (DHAP) & glyceraldehyde 3-phosphate (GAP)

reaction #5 - triose phosphate isomerase catalyzed reaction

enzyme: triose phosphate isomerase

purpose:

1. GAP (starting point) & DHAP (not used)

   1. enzyme converts DHAP to GAP to maintain supply (most catalytically efficient enzyme in glycolysis)

Dihydroxacetone phosphate (DHAP) ——> glyceraldehyde 3-phosphate (GAP)

reaction #6 - glyceraldehyde 3-phosphate dehydrogenase catalyzed reaction

enzyme: glyceraldehyde 3-phosphate dehydrogenase

purpose:

1. make a high phosphoryl transfer potential (PTP) compounds

glyceraldehyde 3-phosphate (GAP) ——> 1,3-bisphosphoglycerate (1,3-BPG)

reaction #7 - phosphoglycerate kinase catalyzed reaction

enzyme: phosphoglycerate kinase

purpose:

1. ATP is generated via substrate level phosphorylation

1,3-bisphosphoglycerate —> 3-phosphoglycerate

reaction #8 - phosphoglycerate mutase catalyzed rraction

enzyme: phosphoglycerate mutase

purpose:

1. working towards creating a high phosphoral transfer compound

3-phosphoglycerate ——> 2-phosphoglycerate

reaction #9 - enolase catalyzed reaction

enzyme: enolase

purpose:

1. make a high phosphoryl transfer potential (PTP) compound

2-phosphoglycerate ——> phosphoenolpyruvate

reaction #10 - pyruvate kinase catalyzed reaction

enzyme: pyruvate kinase

purpose:

1. ATP is generated via substrate-level phosphorylation

phosphoenolpyruvate ——-> pyruvate

What are the two stages of glycolysis?

Stage 1: Investment Stage, Stage 2: Payoff Stage

Stage 1: Investment stage

conversion of glucose to two molecules of glyceraldehyde 3-phosphate (GAP), requires investment of two ATP (trapping and preparation)

Stage 2: Payoff

conversion of two molecules of GAP to two molecules of pyruvate, generates four molecules of ATP and two molecules of NADH