Glycolysis is the metabolic pathway that converts glucose into pyruvate and produces ATP. It occurs in ten steps and involves the conversion of glucose into two three-carbon molecules. The first five steps are the preparatory phase where ATP is consumed, and the last five steps are the payoff phase where ATP is produced, resulting in a net production of two ATP per glucose molecule. Glycolysis also produces two NADH molecules. Disruptions to glycolysis can lead to diseases like diabetes or genetic disorders impacting cellular respiration.

1. GLYCOLYSIS
Meerub Shakil

2. GLYCOLYSIS
Introduction:
➔Glycolysis is the metabolic pathway that converts
Glucose C6H12O6 into Pyruvate CH3COCOO- and a
hydrogen ion H+ .
➔In this process 6 carbon molecule convert into 3
carbon molecule.
➔Glycolysis is a sequence of TEN enzyme-catalyzed
reactions and it is an oxygen-independent metabolic
pathway.
➔

3. GLYCOLYSIS
➔The free energy released in this process is used to
form the high-energy molecules ATP and NADH.
➔In most organisms, Glycolysis occur in Cytosol of
cell.

4. The Glycolysis pathway can be separated
into two phases:
➢The Preparatory Phase ➢The Pay Off Phase
●The preparatory phase in which ATP is
consumed
●The pay off phase in which ATP is produced

5. GLYCOLYSIS SCHEMATIC DIAGRAM

6. STEP OF GLYCOLYSIS
Step 1: A phosphate group is transferred from ATP to glucose,
making glucose-6-phosphate. Glucose-6-phosphate is more
reactive than glucose and addition of the phosphate also traps
glucose inside the cell since glucose with a phosphate can’t
readily cross the membrane.
Step 2: Glucose-6-phosphate is converted into its isomer,
fructose-6-phosphate.
Step 3: Another phosphate group is transferred from ATP to
fructose-6-phosphate, producing fructose-1,6-bisphosphate.
This step is catalyzed by phosphofructose kinase enzyme.
Step 4: Fructose-1,6-bisphosphate splits to form two three
carbon sugars; DHAP dihydroxyacetone phosphate and GAP
glyceraldehyde-3-phosphate.

7. Step 5: DHAP is converted into glyceraldehyde-3-phosphate.
Step 6: Two half reactions occur simultaneously,
Glyceraldehyde-3-phosphate(one of the three carbon
sugars formed in the initial phase is oxidized,
2 NAD+ is reduced to NADH and H+.This energy is
used to phosphorylate the molecule, forming 1,3-
bisphosphoglycerate.
Step 7: 1,3-bisphosphglycerate donates one of its phosphate
group to ADP, making a molecule of ATP and turning into 3-
phospoglycerate n the process.

8. Step 8: 3-phosphoglycerate is converted into its
isomer, 2-phosphoglycerate.
Step 9: 2-phosphoglycerate loses a molecule of
water, becoming phosphoenolpyruvate(PEP), it is
an unstable molecule and lose its phosphate
group in the final step.
Step 10: PEP readily donates its phosphate group
to ADP, making a second molecule of ATP. As it
loses its phosphate and convert into pyruvate(the
end product of glycolysis).

9. Overall products of Glycolysis
CONSUMED = 2ATP
PRODUCED = 4ATP
NET PRODUCT = 2ATP
Two molecules of NADH produced
CONSUMED = 2ATP
PRODUCED = 4ATP
NET PRODUCT = 2ATP
Two molecules of NADH produced

10. GYLCOLYSIS IN DISEASE
➢Diabetes: Cellular uptake of glucose occurs in response to
insulin signal and glucose is subsequently broken down
through glycolysis, lowering blood sugar levels.Glycolysis in
hepatocytes controls hepatic glucose production and when
glucose is overproduced by the liver without having a means
of being broken down by the body, Hyperglycemia results.
➢Genetic Disease: Glycolytic mutations are generally rare
due to importance of the metabolic pathway, this means that
the majority of occurring mutations result in an inability for
the cell to respire and therefore cause the death of the cell at
an early stage. However, some mutations are seen with one
notable example being Pyruvate kinase deficiency, leading to
Chronic Hemolytic Anemia.

11. REFERENCE
i.Hashmi’s Textbook of Medical Biochemistry
ii.Harper’s illustrated Biochemistry
iii.Google search(Glycolysis introduction,steps and
cytosol)