Releasing Chemical Energy - Vocabulary Flashcards

Vocabulary flashcards covering key terms and definitions from the notes on aerobic respiration, glycolysis, the citric acid cycle, oxidative phosphorylation, and fermentation.

Oxidative phosphorylation

ATP production in mitochondria driven by a proton gradient formed as electrons pass through the electron transport chain; oxygen is the final electron acceptor.

Mitochondria

Double-membrane organelles; powerhouses of the cell where oxidative phosphorylation and ATP production occur.

Free radicals

Highly reactive atoms or molecules with unpaired electrons that can damage biomolecules.

Reactive oxygen species (ROS)

Oxygen-containing free radicals formed during metabolism that can cause oxidative stress.

Aerobic respiration

Oxygen-dependent pathway that fully oxidizes glucose to CO2 and H2O, producing ATP.

Anaerobic

Processes occurring in the absence of oxygen.

Glycolysis

First stage of glucose breakdown in the cytoplasm; glucose to two pyruvate with net 2 ATP and 2 NADH.

Pyruvate

End product of glycolysis; transported into mitochondria and, in aerobic conditions, converted to acetyl–CoA with CO2 release and NADH formation.

NADH

Electron carrier that delivers electrons to the electron transport chain; produced in glycolysis and the Krebs cycle.

FADH2

Electron carrier that donates electrons to the electron transport chain; produced in the Krebs cycle.

Acetyl–CoA

Two-carbon acetyl group bound to CoA; enters the citric acid cycle after pyruvate is decarboxylated.

Pyruvate dehydrogenase reaction

Pyruvate is decarboxylated to CO2 and acetyl–CoA; NADH is produced.

Citric acid cycle (Krebs cycle)

Oxidizes acetyl–CoA to CO2 in the mitochondrial matrix; yields ATP, NADH, and FADH2.

Electron transfer phosphorylation

Another term for oxidative phosphorylation; electrons flow through the chain, creating a proton gradient that drives ATP formation.

ATP synthase

Enzyme that uses the proton gradient to synthesize ATP from ADP and Pi.

Oxygen (O2)

Final electron acceptor in the electron transport chain; its reduction forms water.

Water (H2O)

Product formed when oxygen accepts electrons and combines with protons at the end of the electron transport chain.

Carbon dioxide (CO2)

Gas produced during pyruvate decarboxylation and the Krebs cycle; leaves the cell.

Fermentation

Anaerobic pathway that harvests energy from carbohydrates by glycolysis only; occurs in the cytoplasm; yields 2 ATP per glucose and regenerates NAD+.

Alcoholic fermentation

Pyruvate is converted to ethanol and CO2; used in baking and wine/beer production; net 2 ATP from glycolysis.

Lactate fermentation

Pyruvate reduced to lactate; occurs in muscles under anaerobic conditions; regenerates NAD+; net 2 ATP.

NAD+ regeneration

Recycling of NAD+ during fermentation to allow glycolysis to continue without oxygen.

Glycogen

Storage form of glucose; liver converts stored glycogen to glucose between meals to maintain blood glucose.

Ketogenic diet

Very low carbohydrate, high fat diet; ketogenesis converts acetyl–CoA to ketone bodies; studied for metabolic syndrome and neurological disorders.

Fatty acids

Broken down into acetyl–CoA entering the Krebs cycle; yield more ATP than carbohydrates.

Glycerol

Backbone of fat that enters glycolysis.

Fatty acids and glycerol metabolism

Fatty acids feed the Krebs cycle via acetyl–CoA; glycerol feeds glycolysis; fats can yield more ATP than carbohydrates.

NADH and FADH2

Electron carriers produced during glycolysis and the Krebs cycle that feed the electron transport chain.

Oxygen availability and respiration types

Anaerobic = absence of oxygen; Aerobic = presence of oxygen; determines whether glycolysis proceeds to fermentation or to full oxidative phosphorylation.