What is Respiration?

• Respiration is an important chemical reaction in plants, animals and microbes - this means ALL living things respire and respiration is NOT the same as breathing
• Respiration - a chemical reaction that releases energy stored in glucose
• Organisms use the energy to build large molecules from smaller ones (e.g. when a plant makes starch from glucose), to regulate internal body temperature (homeostasis) and to allow muscle contraction and therefore movement
• How are muscle contractions and temperature regulation linked?

  When it's cold, there are small muscle contractions (shivers) that warm up the body. This is because the muscle cells are respiring at a higher rate and therefore release thermal energy
• Aerobic Respiration - when there is enough oxygen being delivered to cells

  • The molecule organisms needed to use to release energy is glucose
  • When this molecule reacts with oxygen, bonds in the glucose molecule break and energy is released
  • To break ALL the bonds in the glucose molecule, 6 molecules of oxygen are needed
  • This energy can then be used to make our muscles contract which allows us to move (or it can be used to build large molecules from smaller ones)
  • The waste products of this reaction are carbon dioxide and water
• The word equation for aerobic respiration is:

  • glucose + oxygen → carbon dioxide + water
• The balanced symbol equation for aerobic respiration is:

  • C6H12O6 + 6O2 → 6CO2 + 6H2O
• Aerobic respiration happens inside the:

  1. Cytoplasm
  2. Cell membrane
  3. Ribosome (site of proteinsynthesis)
  4. Nucleus
  5. Mitochondria

  
• Anaerobic Respiration - When there is not enough oxygen being delivered to cells

  • The molecule the organism needs to release is glucose
  • However, our hearts may not beat fast enough to deliver six molecules of oxygen meaning not all the bonds can be broken
  • Instead, the cell simply breaks the molecule in half without the use of oxygen
  • The product of this breakdown is lactic acid which can cause muscle fatigue
  • Because less bonds are broken in this process, we say the breakdown of glucose is incomplete and as a result, less energy is released in total
• The word equation for anaerobic respiration is:

  • glucose → lactic acid
• Reactant(s)

  Aerobic - glucose and oxygen

  Anaerobic - glucose
• Product(s)

  Aerobic - carbon dioxide and water

  Anaerobic - lactic acid
• Purpose

  Aerobic - release energy

  Anaerobic - release energy
• Amount of energy released

  Aerobic - a large amount

  Anaerobic - a very small amount
• Breakdown of glucose is...

  Aerobic - complete

  Anaerobic - incomplete
• Adverse side effects

  Aerobic - none

  Anaerobic - muscle fatigue