Figure 2.

The Kreb's Cycle and oxidative phosphorylation pathways are central to cell metabolism. Acetyl CoA from many different sources can enter the Kreb's Cycle (also known as the citric acid cycle, or tricarboxylic acid cycle). This pathway not only drives oxidative phosphorylation by regenerating succinate, but it provides many useful intermediates for biosynthesis. The enzyme complexes of the electron transport chain, which support oxidative phosphorylation, are shown embedded in the inner mitochondrial membrane.