The primary source of energy for cells and an essential component of aerobic respiration is the tricarboxylic acid (TCA) cycle, sometimes referred to as the Kreb's or citric acid cycle.
The cycle converts the acetyl coenzyme A (acetyl CoA) chemical energy into the reducing force of nicotinamide adenine dinucleotide (NADH).
For compounds that can transform into an acetyl group or dicarboxylic acid, the cycle acts as a portal for aerobic metabolism.
The three enzymes citrate synthase, isocitrate dehydrogenase, and alpha-ketoglutarate dehydrogenase are involved in three different places where the TCA cycle is regulated.
The cycle also contributes to the replenishment of precursors for the storage form of fuels, such as cholesterol and amino acids.
The final stage of aerobic cellular respiration, known as oxidative phosphorylation, which precedes the Krebs cycle, requires oxygen but is independent of it.
Prior reactions divide organic molecules with energy (carbohydrates, lipids, and proteins).