glycolysis and anaerobic respiration

• Respiration is a chemical reaction. 
• All living cells respire. 
• Sugars are oxidised to release energy. 
• Glucose enters cells via facilitated diffusion. 
• Coenzymes are complex organic molecules used by enzymes to accept or donate molecules involved in a reaction, they are sometimes called helper molecules. 
• C6H12O6 + 6O2 ---> 6CO2 + 6H2O + 32ATP 
• Glycolysis is the splitting of a hexose sugar into 3-carbon molecules. 

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• Stage 1:

  glucose is phosphorylated by adding 2 phosphate molecules from 2 molecules of ATP. ATP is hydrolysed to ADP. This provides the energy to activate and lowers the activation energy for the enzyme controlled reaction. Glucose is split using water and 2 molecules of triose phosphate and 2 molecules of ATP are used up. 
• Stage 2:

  4 ATP molecules are produced but 2 were used at the start, so during glycolysis there is a net gain of 2ATP. Coenzyme NAD collects the hydrogen ions forming 2 NADH. The triose phosphate is oxidised and forms 2 molecule of pyruvate.