Respiration

• Respiration is a series of chemical reactions in the cell which transfer chemical energy from glucose to ATP. ATP can store chemical energy, until it is needed by the cell.

• ATP is the energy source for all life processes like active transport, making molecules eg proteins from amino acid, movement eg muscle contraction, bioluminescence (light production) eg glow worms.

• Respiration can be aerobic or anaerobic. Aerobic respiration produces much greater amounts of ATP per glucose than anaerobic respiration.

Aerobic respiration

• Aerobic respiration needs oxygen for the complete breakdown of glucose into carbon dioxide and water. Energy is released in the form of ATP and heat.
  

  

Respiration occurs in three phases:
• Glycolysis - begins breakdown of glucose, carried out in cytoplasm. No oxygen required
• Krebs cycle - occurs in matrix of mitochondria. Small amount of ATP produced. CO2 released, no oxygen required
• Respiratory or electron transfer chain - occurs in cristae of mitochondria. Hydrogen passed along a series of acceptor molecules to produce a large amount of ATP. Oxygen used at the end of chain to react with hydrogen to produce water.

Anaerobic respiration

• does not require oxygen. Only glycolysis takes place so a small amount of ATP is produced. In animals lack of oxygen causes it.
• Anaerobic respiration in animals produces lactic acid.

• In plants the end product is ethanol and process is fermentation.