Molecular Biology - Cell respiration

Cell respiration is the controlled release of energy from organic compounds to produce $ATP$.

$ATP$ from cell respiration is immediately available as a source of energy in the cell, released by the hydrolysis into $ADP + P_i$.

Anaerobic cell respiration gives a small yield of $ATP$ from glucose. In humans, the waste product is lactate ($C_3H_6O_3$), whereas in yeast and plants, the products are ethanol ($C_2H_5OH$) and carbon dioxide ($CO_2$).

Aerobic cell respiration requires oxygen and gives a large yield of $ATP$ from glucose, involving the link reaction, the Krebs cycle, and the electron transport chain.

Oxidation is the loss of electrons or hydrogen, or the gain of oxygen; Reduction is the gain of electrons or hydrogen, or the loss of oxygen (OIL RIG).

In glycolysis, glucose is phosphorylated and split into two molecules of pyruvate, resulting in a net gain of $2$ $ATP$ and $2$ reduced $NAD$ ($NADH + H^+$).

The link reaction converts pyruvate into acetyl coenzyme A ($Acetyl-CoA$) in the mitochondrial matrix through decarboxylation and oxidation.

In the Krebs cycle, the oxidation of acetyl groups is coupled to the reduction of hydrogen carriers ($NAD^+$ and $FAD$), liberating $CO_2$.

Chemiosmosis occurs in the inner mitochondrial membrane, where $H^+$ ions flow through $ATP$ synthase down their electrochemical gradient to generate $ATP$.

Oxygen is the final electron acceptor in the mitochondrial electron transport chain, combining with $H^+$ to form $H_2O$.