Aerobic respiration, metabolic cycles. Animation showing how a molecule of the simple sugar glucose is progressively degraded and energy extracted and transferred by metabolic cycles occurring in cells and in mitochondria within the cells. The first stage (upper left) is glycolysis, producing pyruvate, the reduced form of nicotinamide adenine dinucleotide (NADH), and adenosine triphosphate (ATP). The oxidation of pyruvate produces more NADH, carbon dioxide (CO2) and acetyl-CoA (acetyl coenzyme-A) that enters the Krebs cycle. This produces more NADH, the reduced form of flavin adenine dinucleotide (FADH2), more CO2, guanosine triphosphate (GTP) and electrons that enter electron transport chains. These energy transfer routes store a large amount of chemical energy in the form of ATP. The oxidised forms of NAD (NAD+) and FAD are regenerated. The diagram also shows the inner and outer mitochondrial membranes, and the inner matrix where key reactions take place. For this animation with labels, see K004/3512. |