Glycolysis: Energy Harvest and Substrate-Level Phosphorylation

Vocabulary terms and definitions focusing on the chemical intermediates, reactions, energy harvest, and substrate-level phosphorylation events of glycolysis.

Fructose 1,6-bisphosphate

A phosphorylated, less stable, and higher-energy molecule formed by expending ATP to activate the sugar, enabling it to break down more easily in subsequent reactions.

Stage 2 of Glycolysis

The energy harvest stage in which fructose 1,6-bisphosphate is cleaved into three-carbon intermediates and processed to yield ATP and NADH.

Dihydroxyacetone phosphate

A three-carbon intermediate formed alongside glyceraldehyde 3-phosphate from the breakdown of fructose 1,6-bisphosphate that is quickly converted into glyceraldehyde 3-phosphate.

Glyceraldehyde 3-phosphate

The three-carbon intermediate produced in stage two of glycolysis, with two molecules proceeding through subsequent oxidation and phosphorylation reactions.

Reaction 6 of Glycolysis

An oxidation-reduction reaction that uses the exergonic energy of oxidation to attach an inorganic phosphate to glyceraldehyde 3-phosphate, producing 1,3-bisphosphoglycerate and reducing $NAD^+$ to $NADH + H^+$.

1,3-bisphosphoglycerate

A high-energy intermediate produced in Reaction 6 that serves as a phosphate donor to ADP to generate the pathway's first ATP.

3-phosphoglycerate

The three-carbon molecule remaining after 1,3-bisphosphoglycerate donates a high-energy phosphate group to ADP in Reaction 7.

2-phosphoglycerate

The rearranged product formed when the phosphate group on 3-phosphoglycerate is shifted over to the middle carbon.

Phosphoenolpyruvate (PEP)

A high-energy three-carbon compound formed via a dehydration reaction from 2-phosphoglycerate; its phosphate bond contains more energy than ATP, allowing it to act as a phosphate donor.

Pyruvate

The final three-carbon end product of glycolysis formed after phosphoenolpyruvate transfers its phosphate to ADP; it retains high bond energy to be further harvested in the Krebs cycle.

Substrate-level phosphorylation

A reaction where a phosphorylated substrate donor (such as 1,3-bisphosphoglycerate or phosphoenolpyruvate) directly transfers a phosphate group to ADP to generate ATP.

Net yield of glycolysis

The net production of $2$ ATP (derived from $4$ ATP produced minus $2$ ATP used) and $2$ NADH molecules per glucose molecule.