ATP production by glycolysis and oxidative phosphorylation.
Glucose is an important fuel for the generation of ATP to satisfy the bioenergetics demands of the cell. The first step of glycolysis involves the phosphorylation of glucose by hexokinase to generate glucose-6-phosphate (G6P). Glycolysis then proceeds as a series of enzymatic reactions that ultimately generate the final product, pyruvate. Depending on cellular activity, pyruvate can have multiple fates in the cell, one of which is to be completely oxidised to CO2 in the mitochondria for the efficient production of ATP. Alternatively, under anaerobic conditions, pyruvate can be converted to lactate which is secreted out of the cell. Pyruvate is also converted to lactate during aerobic glycolysis, a metabolic signature adopted by cells engaging robust growth and proliferation. The alternative fuel galactose can be metabolised by the Leloir pathway to generate G6P that is then further metabolised by glycolysis.