1. Topic 4: Bioenergetics

2. Respiration Learning Objectives:
Recall the equations for aerobic and anaerobic respiration.
Analyse the differences between aerobic and anaerobic respiration.
Explain the term metabolism.

3. Vocabulary Aerobic respiration Anaerobic respiration Exothermic
Endothermic
Oxygen debt (pg. 161)
Fermentation
Metabolism (pg. 165)
Mitochondria (review)
Enzymes (review)

4. Respiration
The process of transferring energy from glucose, which goes on in every cell.
Involve chemical reactions catalysed by enzymes
Exothermic process (releases energy)

5. Energy is Used To…
Build larger molecules from smaller ones (example: proteins are made from amino acids)  this process also makes new cells for growth, repair, and reproduction
Muscle contraction (movement)
Temperature regulation (mammals and birds)

6. Glucose + Oxygen  Carbon Dioxide + Water
Aerobic Respiration
Aerobic means with oxygen
Happens in the mitochondria
Occurs all the time in plants and animals
Glucose + Oxygen  Carbon Dioxide + Water
C6H12O6 + 6O2  6CO2 + 6H2O
Releases a large amount of energy

7. Anaerobic Respiration in Muscles
Happens when there is not a large enough supply of oxygen getting to the muscles.
Happens when you need more energy than can be supplied by aerobic respiration.
Glucose  Lactic Acid
Releases less energy, so only useful in “emergencies”.

8. lactic acid + oxygen  carbon dioxide + water
Oxygen Debt
The amount of extra oxygen the body needs after exercise to react with the build up of lactic acid and remove it from the cells.
lactic acid + oxygen  carbon dioxide + water
Lactic acid is poisonous (it also causes muscle soreness) and needs to be removed.
Breathing rate and heart rate remain high after stopping exercise to “pay back” the oxygen debt.

9. glucose  ethanol + carbon dioxide
Fermentation
The anaerobic respiration in yeast that produces ethanol and carbon dioxide.
Used in industry to produce ethanol (type of alcohol)
glucose  ethanol + carbon dioxide

10. Comparing Aerobic and Anaerobic Respiration
Is oxygen needed?
YES NO
Products?
CO2 + Water
Lactic acid (muscles)
Ethanol + CO2 (yeast)
Amount of energy?
LARGE
SMALL

11. Metabolism
The sum (total) of all the reactions that happen in a cell or the body.
Enzymes control the reactions in metabolism.
Examples of reactions:
Exothermic reactions (such as breaking down large molecules into smaller ones like in respiration) that release energy
Endothermic reactions (such as building large molecules from small ones) use up energy from respiration

12. Summary
Respiration in humans
Respiration in plants

13. Writing Task
Use all of the vocabulary terms to answer the following essay question.
Compare aerobic and anaerobic respiration and explain the importance of respiration in living things.