Glycolysis is the process of splitting a glucose molecule into two, creating ATP. The process can be anaerobic (no oxygen) or aerobic (with oxygen). Glycolysis occurs in the cells' cytoplasm when glucose (C6H12O6) is broken down buy pyruvic acid, (CH3COCO2H). In anaerobic respiration, the process ends with the creation of two additional ATP. The remaining molecules are further broken down in to lactic acid (C3H6O3). In aerobic respiration the products are then moved through the Kreb's cycle.
The Kreb's cycle, also known as the citric acid cycle, is a complex cycle using enzymes to create energy. Most of the compounds involved in the process contain oxygen, carbon and hydrogen. In most animal cells this process occurs in the mitochondria, which contain the enzymes to speed the process. The products of the Kreb's cycle are NADH and ATP. The remaining carbon compounds are oxidized (CO2) and hydrogen atoms, which are then transported to the cytochrome system.
The cytochrome system is located on the cristae of the mitochondria, which are tiny stalks on the outer layer. The reduced hydrogen atoms are put through a process of oxidation and reduction using coenzymes to produce ATP and water as the final products of cellular respiration.