Respiration

• Respiration is a series of enzyme controlled reactions to release chemical energy from glucose
• ATP- energy released from glucose

  ATP can be broken down to release energy for cellular processes

  • muscle cell contraction
  • cell division
  • active transport
  • protein synthesis
• Aerobic respiration- is the breakdown of glucose with the presence of oxygen
• Stage one of aerobic respiration

  • the first stage of aerobic respiration is called Glycolysis
  • oxygen is not needed at this stage
  • occurs in the cytoplasm
  • glucose is converted into two molecules of pyruvate
  • yields two molecules of ATP
• Stage two of aerobic respiration

  • occurs in the mitochondria of all cells.
  • the pyruvate molecules are broken down in the presence of oxygen to form carbon dioxide and water
  • a large number of ATP molecules are made at this stage
  • this stage is enzyme controlled
• Aerobic respiration equation-

  glucose + oxygen ------> carbon dioxide + water + energy
• Anaerobic respiration also called fermentation is the breakdown of glucose in the absence of oxygen.
• Fermentation in animal cells

  • occurs in the cytoplasm
  • glucose is converted into two molecules of pyruvate
  • yields two molecules of ATP
  • when oxygen is absent pyruvate is broken to lactate
  • a reversible reaction- when oxygen is present lactate can be converted back to pyruvate
• Fermentation in plant/ fungal cells

  • occurs in the cytoplasm
  • glucose is converted into two molecules of pyruvate
  • yields two molecules of ATP
  • when oxygen is absent pyruvate is broken down to ethanol and carbon dioxide
  • an irreversible reaction
• Fermentation equations

  glucose ------> pyruvate <------> lactate

  glucose ------> ethanol + carbon dioxide