Lecture 3-7: Citric Acid Cycle and Regulation of Metabolism

Citric Acid Cycle

Also known as the tricarboxylic acid (TCA) cycle and the Krebs cycle; a series of reactions that extracts energy from pyruvate and other molecules.

Oxaloacetate

A four-carbon molecule that is a crucial intermediate in the citric acid cycle.

Acetyl CoA

A central metabolic intermediate formed from pyruvate that enters the citric acid cycle.

Glycolysis

The metabolic process that converts glucose into pyruvate, producing a small amount of ATP and NADH.

Isomerization

A chemical reaction that rearranges the molecular structure of a compound, such as the conversion of citrate to isocitrate.

Decarboxylation

The process of removing a carboxyl group from a molecule, releasing CO2, as seen in isocitrate to alpha-ketoglutarate.

GTP

Guanosine triphosphate; a high-energy molecule synthesized in the citric acid cycle.

NAD+

Oxidized form of nicotinamide adenine dinucleotide, acts as an electron acceptor in metabolic reactions.

FAD

Flavin adenine dinucleotide; an electron carrier that is reduced to FADH2 during the oxidation of succinate.

Malate

An intermediate in the citric acid cycle that is oxidized to regenerate oxaloacetate.

Glycogen

A branched polymer of glucose stored in liver and muscle cells for future energy needs.

Gluconeogenesis

The metabolic pathway that generates glucose from non-carbohydrate precursors, effectively running glycolysis in reverse.

Thioester bond

A high-energy bond found in compounds like succinyl CoA that can release energy when broken.

Coenzyme A (CoA)

A coenzyme that plays a crucial role in the metabolism of fatty acids and the citric acid cycle.

Redox reactions

Chemical reactions involving the transfer of electrons, which are critical for energy production in the citric acid cycle.

Electron transport chain

A series of protein complexes in the mitochondrial membrane that transfer electrons, culminating in ATP synthesis.

Phosphate transfer

The transfer of a phosphate group from a high-energy compound, such as GTP or ATP, to another molecule.

Intermediate

Molecules formed during the course of a reaction that are not the final product, critical in metabolic pathways.

Hormonal regulation

The modulation of biochemical processes by hormones, influencing metabolic pathways like gluconeogenesis and glycogenesis.

Reduced electron carriers

Molecules like NADH and FADH2 that carry electrons to the electron transport chain for ATP production.

Pyruvate

A key intermediate in metabolism that is formed from glucose during glycolysis and can be converted to acetyl CoA.