Cellular Respiration and ATP

Comprehensive vocabulary flashcards covering the structure and function of ATP, the stages of cellular respiration, and detailed biochemical mechanisms of glycolysis and phosphorylation.

Adenosine triphosphate (ATP)

A small, soluble organic molecule with a relative molecular mass of 507 consisting of adenine, ribose, and three inorganic phosphate ($P_i$) groups, functioning as the cell's immediate energy source and short-term energy store.

Inorganic phosphate ($P_i$)

Phosphate groups present in ATP whose presence provides the molecule with its energy-releasing properties when hydrolysed.

Respirometer

A piece of apparatus used in practical work to measure respiration rates and calculate respiratory quotient (RQ) values.

Redox indicator

A chemical substance used in practical investigations to demonstrate the role and activity of hydrogen acceptors.

ATPase

An enzyme that catalyses the hydrolysis of ATP into ADP and inorganic phosphate, releasing free energy as the terminal phosphate bond is broken.

Phosphorylation

The addition of a phosphate group to a molecule via a condensation reaction, making the recipient molecule more reactive and energy-rich.

Anabolic reactions

Metabolic processes that build up polymers from monomers (such as protein and enzyme synthesis), requiring energy supplied by ATP.

Aerobic respiration

A form of cellular respiration that requires oxygen and breaks down glucose to produce carbon dioxide, water, and a large amount of ATP.

Anaerobic respiration

Cellular respiration occurring in the absence of oxygen that produces lactate in animals, or ethanol and carbon dioxide in plants and fungi, with a limited yield of ATP.

Link Reaction

The oxidative decarboxylation of 3-carbon pyruvate in the mitochondrion, converting it into carbon dioxide and 2-carbon acetyl coenzyme A (acetyl CoA).

Krebs cycle

The stage of aerobic respiration in which electrons are stripped off acetyl coenzyme A molecules, producing reduced coenzymes and some ATP.

Electron transport chain

A series of electron carriers situated in the inner mitochondrial membrane where electron and hydrogen ion energy powers ATP synthesis and forms water as a by-product.

Glycolysis

The first stage of cellular respiration occurring in the cytosol without oxygen, converting 6-carbon glucose into two 3-carbon pyruvate molecules with a net yield of 2 ATP and 2 reduced NAD.

Triose phosphate

A 3-carbon phosphorylated sugar produced in glycolysis by the splitting of fructose bisphosphate.

Dehydrogenation reaction

A reaction driven by a dehydrogenase enzyme that removes hydrogen atoms and associated electrons from a substrate, such as triose phosphate.

NADH dehydrogenase

An enzyme located in the inner mitochondrial membrane that removes electrons from reduced NAD ($\text{NADH}$) to initiate the electron transport chain.

Substrate-level phosphorylation

The synthesis of ATP by direct transfer of a phosphate group from a substrate molecule (other than ATP, ADP, or AMP) to ADP, occurring in glycolysis and the Krebs cycle.

Oxidative phosphorylation

The synthesis of ATP from ADP and free inorganic phosphate driven by electron flow and a proton gradient established by redox reactions in the electron transport chain.

Hexokinase

An enzyme that catalyses the phosphorylation of glucose into glucose 6-phosphate (G6P) using 1 ATP, maintaining the intracellular glucose concentration gradient.

Glycerate bisphosphate

A 3-carbon intermediate in glycolysis produced by the oxidation and phosphorylation of triose phosphate, which subsequently yields pyruvate and ATP via substrate-level phosphorylation.

Cytosol

The fluid portion of the cytoplasm where the ten enzyme-driven reactions of glycolysis occur.