Respiration

• Cellular respiration


  The breaking down of food molecules to obtain the stored energy in the foods
• Cellular respiration


  • Oxygen is needed to break down these food molecules
  • The main food oxidized is the glucose
• Processes that the energy produced by breaking down of glucose can be used for


  • Contraction of muscle cells
  • Active transport of molecules in and out of the cells
  • Build large molecules such as proteins
  • Cell division
  • Maintain constant conditions in cells and the body – homeostasis
  • To move molecules against concentration gradients in active transport
  • For the transmission of nerve impulses
• ATP


  The energy released by breaking down of glucose is 'locked up' in the bonds of this molecule
• ATP


  • It can release energy from its bonds very quickly
  • The molecules can be recycled so there is always a ready supply of energy rich ATP in the cell for all processes that need it
• Types of respiration


  • Aerobic respiration
  • Anaerobic respiration
• Aerobic respiration


  Glucose + Oxygen → Carbon dioxide + Water (+ Energy)
• Aerobic respiration


  • It is the "completely breaking down of glucose into carbon dioxide and water to obtain energy by using oxygen"
  • It is a long process which happens inside the mitochondria and the cytoplasm of the cells
  • The steps of these reactions are catalyzed by different enzymes
• Anaerobic respiration in yeast cells

  Glucose → Ethanol + Carbon dioxide (+ Energy)
• Anaerobic respiration in muscle cells

  Glucose → Lactic acid (+ Energy)
• Anaerobic respiration


  • Glucose is not completely broken down
  • Less energy is released
  • It has the advantage of being able to occur in situations where oxygen is short in supply
• Aerobic respiration


  Happens when there is oxygen supply
• Anaerobic respiration


  Happens when there is low/no oxygen supply
• Aerobic respiration


  Produces a lot of energy
• Anaerobic respiration


  Produces less energy
• Aerobic respiration


  Glucose is completely broken down
• Anaerobic respiration


  Glucose is partially broken down
• Aerobic respiration


  Final products are carbon dioxide and water
• Anaerobic respiration in yeast cells and plant cells


  Final products are ethanol and carbon dioxide
• Anaerobic respiration in muscle cells

  Final product is lactic acid
• Experiment 1 demonstrates the production of carbon dioxide by small living organisms
• Experiment 2 demonstrates the production of heat during respiration