Glycolysis | Embden-Meyerhof Pathway
The conversion of glucose or glycogen to pyruvate and lactate is known as glycolysis or Embden-Meyerhof pathway. Lactate is produced from pyruvate only when oxygen supply to tissue is insufficient. Under aerobic conditions pyruvate enters the TCA cycle through acetyl-CoA for further oxidarion of glucose.
All the enzymes involved in glycolytic pathway are found in extramitrocondrial soluble fraction of the cell. The reactions takes place as illustrated below-
1. Hexokinase 2. Glucose phosphate isomerase 3. Phosphofructokinase 4. Aldolase 5. Triose phosphate dehydrogenase 6. Phosphoglycerate 7. Phosphoglyceromutase 8. Enolase 9. Pyruvate kinase 10. Lactate dehydrogenase
Energatics of Glycolysis
| Reaction | Number of ATP formed per mole of glucose |
|---|---|
| Gly-3-phosphate → 1,3-diphosphoglycerate | 6 |
| 1,3-diphosphoglycerate → 3-phosphoglycerate | 2 |
| Phosphoenolpyruvate → Pyruvate | 2 |
Net ATP = 10
ATP consumed in hexokinase and phosphofructokinase reaction = 2
So, Net ATP = 8
In anaerobic glycolysis, the NADH in gly-3-dehydrogenase step is not oxidied in mitochondria and therefore, the net ATP formed will only be 2. Assuming each high energy phosphate bond to be equivalent to 7600 calories, total ammount of energy captured in-
aerobic glycolysis = 8 x 7600 = 60,800 calories.
anaerobic glycolysis = 2 x 7600 = 15,200 calories.
