Citric Acid Cycle and Glyoxylate Cycle

Flashcards covering key terms and concepts from the Citric Acid Cycle and Glyoxylate Cycle, crucial for understanding biochemical energy production and cellular metabolism.

Citric Acid Cycle

The biochemical hub of the cell that oxidizes carbon fuels, primarily in the form of acetyl CoA, to generate ATP and precursors for biosynthesis.

Acetyl CoA

The two-carbon molecule that enters the citric acid cycle and is derived from the metabolism of carbohydrates, fats, and proteins.

Oxaloacetate

A four-carbon molecule that condenses with acetyl CoA at the beginning of the citric acid cycle.

Citrate

The six-carbon tricarboxylic acid formed from the condensation of acetyl CoA and oxaloacetate.

NADH

A high-energy electron carrier produced during the oxidation of substrates in the citric acid cycle.

Succinyl CoA

A four-carbon compound formed during the oxidative decarboxylation of alpha-ketoglutarate.

Oxidative Decarboxylation

The process of losing carbon dioxide while oxidizing a substrate, prevalent in the citric acid cycle.

Substrate-Level Phosphorylation

The direct generation of ATP from a high-energy phosphoryl donor within a metabolic pathway.

Isocitrate

An intermediate formed from citrate that is isomerized before undergoing further oxidation.

Fumarate

A four-carbon intermediate formed from the oxidation of succinate in the citric acid cycle.

Malate

A four-carbon molecule produced from the hydration of fumarate and oxidized back to oxaloacetate.

Aconitase

The enzyme that catalyzes the isomerization of citrate to isocitrate.

Succinate Dehydrogenase

An enzyme that oxidizes succinate to fumarate and is part of the electron transport chain.

Glyoxylate Cycle

A metabolic pathway found in plants and some bacteria that allows the conversion of acetyl CoA into glucose by bypassing decarboxylation steps.

Electron Transport Chain

A series of proteins that transfer electrons from NADH and FADH2 to generate ATP through oxidative phosphorylation.

Cycle Regulation

The control of the citric acid cycle at various stages, primarily through allosteric regulation of key enzymes.

Isocitrate Dehydrogenase

An allosterically regulated enzyme in the citric acid cycle that catalyzes the oxidative decarboxylation of isocitrate.

Dehydrogenase

Referring to enzymes like alpha-ketoglutarate dehydrogenase that play key roles in the decarboxylation steps of the cycle.

Thioester Bonds

High-energy bonds found in compounds like succinyl CoA that drive reactions in metabolic pathways.

Pyruvate

A three-carbon molecule that is converted into acetyl CoA and serves as a precursor to the citric acid cycle.

ATP

The main energy currency of the cell, produced during the citric acid cycle and via oxidative phosphorylation.

GTP

A molecule similar to ATP that can also be formed during the citric acid cycle and used for energy transfer.

Biochemical Hub

A term referring to the central metabolic role of the citric acid cycle in connecting various metabolic pathways.

Anaplerotic Reactions

Reactions that replenish citric acid cycle intermediates when they are drawn off for biosynthesis.

Malonate

A competitive inhibitor of succinate dehydrogenase that can disrupt the citric acid cycle.

Reoxidation of NADH

A critical step in cellular respiration where NADH is oxidized to regenerate NAD+ and produce ATP.

Proton Gradient

An electrochemical gradient created during electron transport that is used to synthesize ATP.

Pyruvate Carboxylase

An enzyme responsible for the carboxylation of pyruvate to produce oxaloacetate, replenishing the citric acid cycle.

Cancer Metabolism

The altered metabolism of tumor cells, which can involve changes in enzymes from the citric acid cycle.

FAD

Another electron carrier used in specific oxidation reactions in the citric acid cycle, primarily involving succinate.

Biomolecule Precursors

Intermediates generated by the citric acid cycle that are essential for the synthesis of amino acids and other biomolecules.