Embden-Meyerhof-Parnas (EMP) Pathway - Glycolysis Flashcards

This flashcard set covers the Embden-Meyerhof-Parnas (EMP) pathway, including individual enzyme reactions, the two phases of glycolysis, and the mechanism and importance of substrate-level phosphorylation in microorganisms.

Embden-Meyerhof-Parnas (EMP) Pathway

Commonly called glycolysis, it is the principal pathway used by bacteria, fungi, plants, and animals to metabolize glucose to produce energy.

Gustav Embden, Otto Meyerhof, and Jakub Karol Parnas

The three scientists who described the EMP pathway and for whom it is named.

Preparatory (Investment) Phase

Steps 1–4 of the EMP pathway that require the input of two ATP molecules to phosphorylate and break down glucose.

Payoff Phase

Steps 5–10 of the EMP pathway that generate four ATP and two NADH molecules.

Hexokinase / Glucokinase

The enzyme that phosphorylates glucose using 1 ATP to form Glucose-6-phosphate in the first step of glycolysis.

Phosphoglucose isomerase

The enzyme responsible for converting Glucose-6-phosphate into Fructose-6-phosphate.

Phosphofructokinase (PFK)

An enzyme that converts Fructose-6-phosphate to Fructose-1,6-bisphosphate using 1 ATP; it is the rate-limiting and committed step of glycolysis.

Aldolase

The enzyme that splits Fructose-1,6-bisphosphate into two 3-carbon molecules: Glyceraldehyde-3-phosphate (G3P) and Dihydroxyacetone phosphate (DHAP).

Triose phosphate isomerase

The enzyme that converts Dihydroxyacetone phosphate (DHAP) into a second molecule of Glyceraldehyde-3-phosphate (G3P).

Glyceraldehyde-3-phosphate dehydrogenase

The enzyme that converts G3P to 1,3-Bisphosphoglycerate, producing 1 NADH per G3P molecule.

Phosphoglycerate kinase

The enzyme that converts 1,3-Bisphosphoglycerate to 3-Phosphoglycerate, producing 1 ATP via substrate-level phosphorylation.

Phosphoglycerate mutase

The enzyme that catalyzes the conversion of 3-Phosphoglycerate to 2-Phosphoglycerate.

Enolase

The enzyme that converts 2-Phosphoglycerate into Phosphoenolpyruvate (PEP).

Pyruvate kinase

The final enzyme in glycolysis that converts Phosphoenolpyruvate (PEP) to Pyruvate, producing 1 ATP.

Net products of EMP pathway

The overall yield from one molecule of glucose is $2$ molecules of pyruvate, $2$ net ATP, and $2$ NADH.

Substrate-level phosphorylation

A metabolic process where a phosphate group is directly transferred from a high-energy chemical intermediate to ADP to form ATP without an electron transport chain.

Oxidative phosphorylation

A process where ATP synthase uses a proton gradient and an electron transport chain to form ATP; requires oxygen in aerobic respiration.

Succinyl-CoA synthetase

An enzyme in the Citric Acid (TCA) cycle that generates one molecule of GTP (or ATP) per turn by converting succinyl-CoA into succinate via substrate-level phosphorylation.

Fermentation

A process where microbes rely exclusively on substrate-level phosphorylation for ATP generation because they lack an electron transport chain.

Phosphoenolpyruvate (PEP)

A high-energy phosphorylated substrate in the final step of glycolysis used to generate ATP and pyruvate.