Glycolysis

is a metabolic pathway that forms the base for both aerobic and anaerobic respiration. In this process, glucose is converted into pyruvate. Pyruvate is a six-membered ring molecule and formed after the breakdown of carbohydrates into sugars. It is a multi-step process and occurs in the cytoplasm of animal and plant cells. Glycolysis occurs in the cytosol of the cell. It creates ATP without the use of oxygen but can occur in the presence of oxygen also. It breaks down one molecule of glucose, (a 6-carbon molecule) into two molecules of pyruvate, (a 3-carbon molecule) in a controlled manner enzymatic reactions. After the breakdown, glucose becomes the main fuel for the cell. Following are the steps of glycolysis

1.The first step in glycolysis is the conversion of D-glucose into glucose-6-phosphate. Hexokinase is the enzyme catalyst here.

2. The rearrangement of glucose 6-phosphate (G6P) into fructose 6-phosphate (F6P) takes place in this second step.

3. Fructose 6-phosphate is converted into fructose 1,6-bisphosphate using magnesium as a cofactor.

4.The enzyme Aldolase splits fructose 1, 6-bisphosphate into two sugars that are isomers of each other. These two sugars are dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (GAP).

5.The enzyme triphosphate isomerase rapidly inter- converts the molecules dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (GAP).

The above five steps are considered as a preparatory phase

6.Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) dehydrogenates and adds an inorganic phosphate to glyceraldehyde 3-phosphate, producing 1,3-bisphosphoglycerate.

7. A phosphate group from 1,3-bisphosphoglycerate is transferred to ADP to form ATP and 3-phosphoglycerate.

8. P from 3- phosphoglycerate from the 3rd carbon to the 2nd carbon to form 2-phosphoglycerate is relocated in this step.

9. A molecule of water is removed from 2-phosphoglycerate to form phosphoenolpyruvic acid (PEP) by an enzyme enclose.

10. A P from phosphoenolpyruvate (PEP) to ADP to form pyruvic acid and ATP.

The last five steps are known as the pay off phase.