Respiration- Glycolysis

Respiration- Glycolysis

·         Glycolysis is the initial stage of both aerobic and anaerobic respiration.

·          It occurs in the cytoplasm of all living cells.

·          It is the process by which a hexose sugar usually glucose is split into two carbon-3 molecules called pyruvate.  

The Process

1.       The activation of glucose by Phosphorylation

Glucose by itself is not reactive enough to be split. It must be made more reactive and this is done by its bonding to two phosphate molecules that come from the breakdown of ATP (that then becomes ADP)

2.       Splitting of the phosphorylated Glucose

Each glucose is split into two triose phosphate molecules.

3.       Oxidation of Triose phosphate

Hydrogen is removed from each triose phosphate molecules and is transferred to a hydrogen carrier molecule known as NAD to form reduced NAD

4.       The production of ATP

Enzyme controlled reactions convert each triose phosphate molecules into the 3-cardon molecule pyruvate .

Glucose --> 2 Triose Phosphate --(enzymes )--> 2Pyruvate

Energy Yield From Glycolysis

This is the yield for one glucose molecule.

Produced are :

2 molecules of ATP

4 molecules are produced but then two are used up in the Phosphorylation of glucose.

Two molecules of reduced NAD

Which are used later during the electron transport chain.

Two molecules of pyruvate

Which then go to the link reaction in aerobic respiration and help oxidise NAD in anaerobic respiration.