Fig. 1

Metabolism supports energy homeostasis and biosynthesis. Cellular metabolism can be configured to efficiently generate energy in the form of adenosine triphosphate (ATP). Glucose is metabolised by glycolysis to pyruvate (generating 2 ATP), which in turn can be used to fuel oxidative phosphorylation (OXPHOS). Pyruvate is converted to Acetyl-CoA in the mitochondria, which fuels metabolic cycles to generate the reducing equivalents NADH and FADH₂ (not shown) to drive OXPHOS (generating > 30 ATP). Fatty acids are broken down in the mitochondria through a process called β-oxidation that yields acetyl-CoA. Glutamine can also be a fuel for mitochondrial OXPHOS. In addition to fuelling ATP synthesis, glucose and glutamine can also be metabolised and used to support biosynthetic processes. Metabolic intermediates can be diverted into pathways to generate biosynthetic precursors important for the synthesis of lipids, nucleotides and proteins. Glucose can also be diverted into the pentose phosphate pathway (PPP) which is important for nucleotide synthesis and the generation of NADPH. NADPH is an important cofactor for biosynthetic pathways and for the reduction of glutathione, which quenches reactive oxygen species thus supporting redox balance