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Aerobic and anaerobic respiration
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Respiration is a chemical reaction that happens in every living cell, all the time. It releases the energy that cells need.
Aerobic respiration
Aerobic respiration uses oxygen.
glucose + oxygen → carbon dioxide + water (energy released)
It happens in the mitochondria. It releases energy for moving, growing, keeping warm and building molecules.
Respiration is not the same as breathing: breathing moves air in and out of the lungs; respiration is a reaction in cells.
glucose + oxygen → carbon dioxide + water (energy released)
It happens in the mitochondria. It releases energy for moving, growing, keeping warm and building molecules.
Respiration is not the same as breathing: breathing moves air in and out of the lungs; respiration is a reaction in cells.
Anaerobic respiration
Anaerobic respiration happens without oxygen.
In muscles during hard exercise: glucose → lactic acid. Lactic acid can make muscles ache, and you breathe hard afterwards to get oxygen to break it down.
In yeast (fermentation): glucose → ethanol + carbon dioxide. The carbon dioxide makes bread rise; the ethanol is the alcohol in beer and wine.
In muscles during hard exercise: glucose → lactic acid. Lactic acid can make muscles ache, and you breathe hard afterwards to get oxygen to break it down.
In yeast (fermentation): glucose → ethanol + carbon dioxide. The carbon dioxide makes bread rise; the ethanol is the alcohol in beer and wine.
Comparing them
Both types release energy from glucose, but in different ways.
Why do sprinters keep breathing hard after a race has ended?
- During the sprint, muscles respired anaerobically and made lactic acid.
- Oxygen is needed to break down the lactic acid.
- So they breathe hard to take in extra oxygen.
Answer: To take in extra oxygen to break down the lactic acid made by anaerobic respiration.
Aerobic: glucose + oxygen → carbon dioxide + water, in mitochondria, lots of energy. Anaerobic in muscles: glucose → lactic acid, less energy. In yeast: glucose → ethanol + carbon dioxide (fermentation).
The interactive lesson includes the diagrams for this topic.
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