Glycolysis | Biochemistry | Carbohydrates |

The process in which sequence of reaction converting glucose or glycogen into pyruvate or lactase with the production of ATP.

  • The complete pathway of glycolysis is describe in 1940.
  • The pathway is called Embden-Meyerhof and Parans pathway or E.M.P pathway.
  • Occurs – extra mitochondrial membrane.
  • Common for both aerobic and anaerobic respiration.

Glycolysis can be broken down into three stages.

  • Stage (i)

   Trape the glucose molecule in the cell and destabilizes its structure.

  • Stage (ii)

   Break down the glucose into smaller components.

  • Stage (iii)

  Harvests the energy to form ATP molecules and pyruvates.

Followings are the important points.

1. Aims to transform glucose into fructose -1,6-bisphosphate in three different steps;

  • Phosphorylation of glucose

   Glucose moves into the cell with the help of a membrane transporter.

  • One inside the cytoplasm it undergoes a phosphorylation process that is catalyzed by protein called hexokinase

This steps is significant for two reasons;

  • Makes glucose more polar which transport glucose inside the cell.
  • Addition of a charged moiety on to the glucose destablizes the structures and increases its energy and makes more reactive and more likely to undergo glycolysis.
  • Enzyme phosphorylase isomerase transform an aldolase into ketose group.
  • Glucose – 6- phosphate  into Fructose – 6- phosphate
  • Phospho fructokinase add a second phosphoryl group onto the sugar.

2. Break down the glucose into smaller component.

  • An enzyme called aldolase catalyzes the breakdown of fructose 1,6-bisphosphate into two different three carbon molecules glyceraldehyde-3-phosphate and dihydroxy acetone phosphate (DHAP).
  • The glyceraldehyde lies directly on the glycolytic pathways, which means it can go directly to stage 3 of glycolysis without any further change.
  • However the dihydroxy acetone does not.
  • This means that if the DHAP is not modified in anyway it will not be able to continue glycolysis and there fore will not be used to form ATP energy molecule.
  • To prevent the loss of energy potential, the DHAP must be transformed into GAP.

3. Harvest the energy in glyceraldehyde 3- p to form ATP  and NADP and pyruvate molecule.
It consist of five different steps.

  1. Conversion of GAP to 1,3-BPG
  2. Phosphoryl transfer by 1,3-BP to ATP.(substrate level phosphorylation)
  3. Conversion to 2-phosphoglycerate.
  4. Conversion to phosphoryal pyruvate. 
  5. Pyruvate kinase catalyzes the phosphoryl transfer from the high potential PEP molecule onto ADP. This form pyruvate.   

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