Glycolysis is a process of oxygen-free incomplete splitting of glucose. This is the splitting of organic substances that were formed during the preparatory stage (proteins split into amino acids, carbohydrates - to glucose, fats - to glycerin and carboxylic acids, nucleic acids - to nucleotides). This is the main metabolic pathway in those cells that are not capable of photosynthesis.
The process of glycolysis occurs in the cytoplasm of the cell. This is a complex process that consists of 10 reactions. First of all, glucose is dehydrated (hydrogen acceptor is coenzyme NAD+. Then, as a result of enzymatic processes, glucose is converted into 2 molecules of pyruvic acid. In this case, 2 molecules of ATP are formed and the reduced form of hydrogen carrier NAD·H2:
C6H12O6 + 2ADF + 2H3PO4 + 2 NAD+ → 2C3H4O3 + 2ATF + 2H2O + 2NAD·H2.
The further fate of pyruvic acid depends on the presence of oxygen in the cell. If there is no oxygen, the yeast and plants undergo alcoholic fermentation, in which acetic aldehyde and then ethanol are first produced:
1. С3Н4О3 → СО2 + СН3СОН,
2. CH3SON + NAD·H2 → C2H5OH + NAD+.
In animals and some bacteria with a lack of oxygen, lactic acid fermentation occurs with the formation of lactic acid:
C3H4O3 + NAD·H2 → C3H6O3 + NAD+.
As a result of the glycolysis of one glucose molecule, 200 kJ are released, of which 120 kJ is dissipated as heat, and 80% is stored in ATP bonds.
Glycolysis performs 2 functions:
· ATP generation due to glucose splitting;
· delivers building material for fusion reactions.