Question

Explain the major steps of Glycolysis. Why does this process occur in a cell?

Answer 1

Glycolysis is the metabolic process by which glucose is converted into pyruvate. This is the foundation for both aerobic and anaerobic cellular respiration. It results in the formation of energy-rich molecule ATP. It occurs in 10 steps.

Step I: The first step in glycolysis is the conversion of D-glucose into glucose-6-phosphate. Hexokinase enzyme catalyzes this reaction.

Step II: In this, the rearrangement of glucose 6-phosphate (G6P) into fructose 6-phosphate (F6P) takes place by glucose phosphate isomerase enzyme.

Step III: Phosphofructokinase enzyme in presence of Mg${}^{+}$ ion converts fructose 6-phosphate into fructose 1,6-bisphosphate.

Step IV: Enzyme Aldolase splits fructose 1, 6-bisphosphate into two sugars, namely dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (GAP).

Step V: Enzyme triophosphate isomerase interconverts the dihydroxyacetone phosphate (DHAP) into glyceraldehyde 3-phosphate (GAP).

Step VI: Enzyme glyceraldehyde-3-phosphate dehydrogenase converts glyceraldehyde 3-phosphate into 1,3-bisphosphoglycerate. In this step, NADH${}^{+}$ is formed.

Step VII: Enzyme phosphoglycerate kinase converts 1,3-bisphosphoglycerate to 3-phosphoglycerate. In this step, ATP is formed.

Step VIII: Enzyme phosphoglyceromutase converts 3- phosphoglycerate to 2-phosphoglycerate.

Step IX: Enzyme enolase removes a molecule of water from 2-phosphoglycerate to form phosphoenolpyruvic acid (PEP).

Step X: Enzyme pyruvate kinase 2 molecules of pyruvic acids are formed from phosphoenolpyruvate (PEP). In this step, ATP is formed.