Glykys (sweet/sugar)+ Lysis (splitting) = Glycolysis
A molecule of glucose is degraded in a very series of enzyme catalyzed reactions to yield two molecules of the three carbon compound pyruvate.
Scientists – 1930
- Glycolysis was the first metabolic pathway to be elucidated and is probably the best understood.
- It is an almost universal central pathway of glucose catabolism, the pathway with the largest flux of carbon in most cells.
- It’s occurs in all living organisms.
Step wise events of Glycolysis
The breakdown of the 6 carbon glucose into two molecules of the 3 carbon pyruvate occurs in 10 steps, the first 5 of which constitute the preparatory phase.
In this reactions, glucose is first phosphorylated at the hydroxyl group on C-6.
The D-glucose 6- phosphate thus formed is converted to D-fructose 6- phosphate.
Which is again phosphorylated, now at C-1, to yield D-fructose 1,6- bisphosphate.
Fructose 1,6-bisphosphate is split to yield two three- carbon molecules, dihydroxyacetone phosphate & glyceraldehyde 3-phosphate; this is the “lysis” step that gives the pathway its name.
The dihydroxyacetone phosphate is isomerized to a second molecule of glyceraldehyde 3-phosphate, ending the primary phase of Glycolysis. The energy gain comes within the payoff phase of Glycolysis.
Each molecule of glyceraldehyde 3-phosphate is oxidized & phosphorylated by inorganic phosphate to form 1,3- bisphosphoglycerate.
Energy is then released because the two molecules of 1,3- bisphosphoglycerate are converted to 2 molecules of pyruvate.
- Degradation of glucose to yield pyruvate.
- Phosphorylation of ADP to ATP.
- Transfer of a hybrid ions to NAD+, forming NADH.
Glucose + 2NAD+ + 2ADP + 2Pi —–> 2 Pyruvate + 2NADH + 2H+ + 2ATP + 2H2O.