Glycolysis

This set of vocabulary flashcards covers the enzymes, metabolites, and regulatory mechanisms of the glycolysis pathway as presented in the Keele University lecture.

Glycolysis

The metabolic pathway that converts glucose ($C_6$) into two molecules of pyruvate ($C_3$).

SGLT

The $Na^+$-glucose transporter responsible for bringing glucose into cells.

GLUT

A glucose transporter that is $Na^+$-independent.

Standard Free Energy Change ($\Delta G^{o \prime}$)

The free energy change of a reaction under standard conditions ($298\,K$, $1\,atm$, $1\,M$ concentration).

Actual Free Energy Change ($\Delta G$)

The free energy change occurring under intracellular conditions, which determines the direction and spontaneity of a reaction.

Hexokinase

The enzyme in all cells that catalyzes Step 1 by adding a phosphate group to glucose, trapping it inside the cell as Glucose-6-phosphate.

Kinase

An enzyme that adds a phosphate group to a substrate using ATP as the donor.

Phosphoglucose isomerase

The enzyme that catalyzes Step 2, the reversible isomerization of Glucose-6-phosphate to Fructose 6-phosphate.

Phosphofructokinase (PFK)

The primary control enzyme of glycolysis that catalyzes the irreversible conversion of Fructose 6-phosphate to Fructose 1,6-bisphosphate.

Aldolase

The enzyme that splits the six-carbon hexose Fructose 1,6-bisphosphate into two three-carbon trioses: DAP and GAP.

Triose-phosphate isomerase (TIM)

A 'perfect enzyme' whose reaction rate is diffusion controlled; it maintains equilibrium between Dihydroxyacetone phosphate (DAP) and Glyceraldehyde-3-phosphate (GAP).

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH)

The enzyme that catalyzes the oxidation of GAP to 1,3-Bisphosphoglycerate, producing NADH in the process.

Phosphoglycerate kinase

The enzyme responsible for the first substrate-level phosphorylation, generating ATP from 1,3-Bisphosphoglycerate and ADP.

Phosphoglycero-mutase

The enzyme that catalyzes the reversible shift of the phosphoryl group from 3-Phosphoglycerate to 2-Phosphoglycerate.

Enolase

The enzyme that catalyzes the dehydration of 2-Phosphoglycerate to create the energy-rich compound Phosphoenolpyruvate (PEP).

Pyruvate kinase

The enzyme that catalyzes the final irreversible step of glycolysis, producing ATP and Pyruvate from PEP and ADP.

Substrate-level phosphorylation

The chemical coupling of the hydrolysis of high-energy reactants to the phosphorylation of ADP to form ATP.

Allosteric Regulation of PFK

Activity is increased by high AMP levels and decreased by high ATP or Citrate levels.

Anaerobic Glycolysis

The process occurring in the absence of oxygen where NADH reacts with Pyruvate to form Lactate and recycle $NAD^+$.

Gluconeogenesis

The metabolic process of synthesizing glucose from non-carbohydrate nutrients like amino acids, essentially reversing glycolysis through workarounds for irreversible steps.

Cytosol

The specific compartment of the cell where the reactions of glycolysis take place.

Overall Net Reaction of Glycolysis

$$\text{Glucose} + 2NAD^+ + 2ADP + 2Pi \rightarrow 2NADH + 2\text{pyruvate} + 2ATP + 2H_2O + 4H^+$$