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glycolysis-130830124335-phpapp01.pptxGlycolysis
By
Asar Khan
M.Sc (zoology)
AWKUM
Definition
Derived from Greek word
Glykys = Sweet
Lysis = splitting
The process in cell metabolism by which
carbohydrates and sugars, especially
glucose, are broken down, producing Glucose = (C6H12O6)
ATP and pyruvic acid and two "high
energy" electron carrying molecules
of NADH.
10 Steps involves in Glycolysis
Step 1
The enzyme hexokinase phosphorylates (adds a phosphate group to) glucose in the cell's cytoplasm.
Step 2
The enzyme phosphoglucoisomerase converts glucose 6-phosphate into its isomer fructose 6-phosphate.
Step 3
The enzyme phosphofructokinase uses another ATP molecule to transfer a phosphate group to fructose 6-phosphate to form fructose 1, 6-bisphosphate.
Step 4
The enzyme aldolase splits fructose 1, 6-bisphosphate into two sugars that are isomers of each other. These two sugars are dihydroxyacetone phosphate and glyceraldehyde phosphate.
Step 5
The enzyme triose phosphate isomerase rapidly inter-converts the molecules dihydroxyacetone phosphate and glyceraldehyde phosphate.
Glyceraldehyde phosphate is removed / used in next step of Glycolysis.
Net result for steps 4 and 5:
Fructose 1, 6-bisphosphate↔ 2 molecules of Glyceraldehyde phosphate (C3H5O3P1)
Step 6
enzyme triose phosphate dehydrogenase
enzyme transfers a hydrogen (H-) from glyceraldehyde phosphate to (NAD+) to form NADH.
Triose phosphate dehydrogenase + 2 H- + 2 NAD+ → 2 NADH + 2 H+
Next triose phosphate dehydrogenase adds a phosphate (P) from the cytosol to the oxidized glyceraldehyde phosphate to form
1, 3-bisphosphoglycerate.
TPD+ 2P + 2 glyceraldehyde phosphate → 2 molecules of 1,3-bisphosphoglycerate
Step 7
The enzyme phosphoglycerokinase transfers a P from
1,3-bisphosphoglycerate to a molecule of ADP to form ATP
This happen for each molecule of 1,3-biphosphoglycerate
Result in step 6: 2 molecules of 3-phosphoglycerate (C3H5O4P1) + 2 ATP
Step 8
The enzyme phosphoglyceromutase relocates the P from 3-phosphoglycerate from the 3rd carbon to the 2nd carbon to form
2-phosphoglycerate.
2 molecules of 2-Phosphoglycerate (C3H5O4P1)
Step 9
The enzyme enolase removes a molecule of water from 2-phosphoglycerate to form phosphoenolpyruvic acid (PEP).
Result: 2 molecules of C3H3O3P1
Step 10
The enzyme pyruvate kinase transfers a P from PEP to ADP to form pyruvic acid and ATP
Result in step 10: 2 molecules of 2 ATP + 2NADH
| Net energy | ATP utilized | ATP produced | |
| 2 ATP | 2ATP From glucose to glucose -6-p. From fructose -6-p to fructose 1,6 p. | 4 ATP (Substrate level phosphorylation) 2ATP from 1,3 DPG. 2ATP from phosphoenol pyruvate | In absence of oxygen (anaerobic glycolysis) |
| 6 ATP Or 8 ATP | 2ATP -From glucose to glucose -6-p. From fructose -6-p to fructose 1,6 p. | 4 ATP (substrate level phosphorylation) 2ATP from 1,3 BPG. 2ATP from phosphoenol pyruvate. | In presence of oxygen (aerobic glycolysis) |
| + 4ATP or 6ATP (from oxidation of 2 NADH + H in mitochondria). |
Energy Production of Glycolysis
