The Krebs cycle starts when acetyl CoA reacts with the compound oxaloacetate to form citrate and release coenzyme A, explains Encyclopedia Britannica. The Krebs cycle is also called the tricarboxylic acid cycle and the citric acid cycle.
The Krebs cycle is the second stage of cellular respiration. Cellular respiration is a three-stage process in which living cells break down organic fuel molecules in the presence of oxygen to harvest the energy they need to grow and divide. This process occurs in most plants, animals, fungi and many bacteria. In all organisms except bacteria, the Krebs cycle is carried out in the mitochondria, which is a matrix of intracellular structures. The Krebs cycle was proposed by the biochemist Sir Hans Adolf Krebs in 1937.