Glycolysis in respiration

Glycolysis is the first stage of breakdown of glucose in anaerobic and aerobic respiration; it occurs in in absence of oxygen.

Glycolysis represents a series of reactions in which a glucose molecule is broken down into two molecules of pyruvate.  Glycolysis occurs in the cytoplasm of cells, not in the mitochondria, and does not require the presence of oxygen.  The process may be subdivided into two steps, first the conversion of glucose into fructose 1,6 – di-phosphate, and secondly the splitting of fructose -1,6- di-phosphate into 3C sugars which are later converted into pyruvate.  Two ATP molecules are used up for phosphorylation reaction in the first step.  Whilst four ATP molecules are produced in the second step.  Four hydrogen atoms are also release.  These are oxidized to water by molecular oxygen with accompanying phosphorylation of ADP to ATP molecules during oxidative. Each pair of hydrogen atom is oxidized to form 2 ATP

The ultimate fate of pyruvate depends on the availability of oxygen in the cell.  If it is present, pyruvate will enter a mitochondrion and be completely oxidized into carbon dioxide and water aerobic respiration.  If oxygen is unavailable pyruvate will be converted into ethanol or lactate (anaerobic respiration).

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Dr. Bbosa Science