lecture 23 biochem

Glycolysis

A sequence of 10 enzyme-catalyzed reactions by which one molecule of glucose is converted to 2 molecules of pyruvate, with the net production of 2 ATP and the reduction of 2 NAD+ to 2 NADH.

Flux control points

Enzymes that function with large negative free energy changes, which determine the flow of metabolites through a pathway.

Phosphofructokinase (PFK)

The primary flux control point for glycolysis, inhibited by ATP and activated by AMP and ADP.

Homolactic fermentation

A process under anaerobic conditions where pyruvate is reduced to lactate, regenerating NAD+ for glycolysis.

Alcoholic fermentation

A metabolic process where pyruvate is decarboxylated and then reduced to ethanol,

Pentose phosphate pathway (PPP)

A metabolic pathway that oxidizes glucose-6-phosphate to produce NADPH and ribose-5-phosphate.

Electron carriers

Molecules like NAD+ and FAD that accept electrons from reduced metabolites and are essential in metabolic pathways.

Regulatory enzymes

Enzymes such as hexokinase, phosphofructokinase, and pyruvate kinase that regulate metabolic pathways and are often subject to allosteric regulation.

Isomerization

A biochemical process where molecules convert to different structural forms, such as glucose to fructose.

Tautomerization

A chemical reaction that results in the interconversion of tautomers, often involving the relocation of a hydrogen atom.

Epimers

A specific type of stereoisomer that differ in configuration at only one specific carbon atom.

Antagonistic regulation

Regulation mechanism where one pathway (e.g., glycolysis) is inhibited when the other pathway (e.g., gluconeogenesis) is active.

Reversible reactions

Reactions that can proceed in either direction depending on conditions, such as glycolytic and gluconeogenic pathways.

Acyl phosphate

A high-energy compound formed during the oxidation of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate.

Dihydroxyacetone phosphate (DHAP)

A glycolytic intermediate that can isomerize to glyceraldehyde 3-phosphate (GAP).

Pyruvate kinase

An enzyme that catalyzes the last step of glycolysis, generating ATP from ADP and phosphoenolpyruvate (PEP).

ATP synthesis

The process of forming adenosine triphosphate (ATP) from adenosine diphosphate (ADP) and inorganic phosphate (Pi), primarily through glycolysis.

Fate of pyruvate

Pyruvate can undergo oxidation in aerobic conditions or be reduced to lactate or ethanol in anaerobic conditions.

Decarboxylation

The removal of a carboxyl group from a molecule, such as in the conversion of pyruvate to acetaldehyde in alcoholic fermentation.