Respiration

Respiration

• What is it? The process by which living things use food molecules (such as glucose) to produce energy
  • How? The energy comes from breaking bonds
• Where does it happen? In the cell
• Why is it needed? Respiration provides energy for all life processes such:
  • Maintaining body temperature
  • Muscle contraction
  • Building molecules
  • Active transport
  • Many others

Note: "Respiration" = breathing,
"Cellular Respiration" = The chemical process

Aerobic vs. Anaerobic Respiration

• Doesn't use oxygen
• Faster
• Glucose only incompletely broken down
• Less energy released

• Requires oxygen
• Slower
• Glucose broken down completely
• More energy released

Aerobic

Anaerobic

• Anaerobic respiration happens when oxygen is less/absent, or faster energy release is required
  • Intense exercise
  • Diving mammals (whales, dolphins)
  • Germinating seeds in the soil

• Aerobic respiration supplies most of the energy in plant and animal cells

Aerobic respiration

• Glucose + Oxygen ----> Water + Carbon dioxide + Energy

• Glucose from food
• Oxygen from air
• Water excreted or recirculated in the body by kidney
• Carbon dioxide breathed out
• A lot of energy is released
  

Anaerobic respiration

• In animal cells:
  • glucose -> lactic acid + energy
• In plant cells:
  • glucose -> ethanol + carbon dioxide
• In fungi, same reaction as plant cells
  • Breadmakers use yeast to make bread light and spongy.
    • How? Yeast in bread releases carbon dioxide

(Sometimes also called fermentation)