Overview
This lecture explains cellular respiration, how organisms use its energy, and compares aerobic and anaerobic respiration, including their processes and uses.
What is Respiration?
- Respiration is the process of releasing energy from glucose in living cells.
- It is an exothermic reaction, meaning it releases energy.
- Energy is transferred, not created, during respiration.
Uses of Energy from Respiration
- Energy is used to build larger molecules from smaller ones, such as proteins from amino acids.
- Muscular contraction requires energy for movement.
- Maintaining steady body temperature also relies on respiration energy.
- Many essential body reactions depend on energy from respiration.
Types of Respiration
- Two main types: aerobic (with oxygen) and anaerobic (without oxygen) respiration.
Aerobic Respiration
- Requires sufficient oxygen to occur.
- Most efficient way to transfer energy from glucose.
- Occurs continuously in plants and animals, within the mitochondria.
- Word equation: glucose + oxygen → carbon dioxide + water.
- Chemical equation: C6H12O6 + 6O2 → 6CO2 + 6H2O.
Anaerobic Respiration in Humans
- Occurs without oxygen, typically during intense exercise.
- Word equation: glucose → lactic acid.
- Less efficient since glucose is only partially broken down.
- Produces toxic lactic acid which must be removed from the body.
Anaerobic Respiration in Plants and Yeast (Fermentation)
- Word equation: glucose → ethanol + carbon dioxide.
- In yeast, called fermentation; used for making bread, beer, and wine.
- Carbon dioxide causes bread to rise, and ethanol is used for alcoholic drinks.
Key Terms & Definitions
- Cellular Respiration — Process that releases energy from glucose in cells.
- Exothermic Reaction — A reaction that releases energy.
- Aerobic Respiration — Respiration with oxygen, producing CO2 and water.
- Anaerobic Respiration — Respiration without oxygen, producing lactic acid (in animals) or ethanol and CO2 (in plants/yeast).
- Mitochondria — Subcellular structures where aerobic respiration occurs.
- Fermentation — Anaerobic process in yeast producing ethanol and CO2.
Action Items / Next Steps
- Review word and chemical equations for both types of respiration.
- Learn where each type of respiration occurs and its products.