Introduction to Respiration
Year 7 ๐ฌ Cell Biology & Biochemistry Aerobic and anaerobic respiration and energy release.
โก Aerobic Respiration
Aerobic respiration releases energy from glucose using oxygen. It is the main energy-releasing process in most organisms.
Word equation
glucose + oxygen โ carbon dioxide + water (+ energy released as ATP)Symbol equation
$$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O$$- Occurs mainly in mitochondria
- Releases ~38 ATP per glucose molecule
- Products (COโ and HโO) are excreted
- Sustained energy supply for long-duration activity
โก Anaerobic Respiration
When oxygen supply is insufficient (e.g. during intense exercise), cells switch to anaerobic respiration โ less efficient but immediate.
In muscles (animals)
glucose โ lactic acid (+2 ATP)In yeast (fermentation)
glucose โ ethanol + carbon dioxide (+2 ATP)Oxygen debt: After intense exercise, extra oxygen is needed to oxidise accumulated lactic acid back to COโ + HโO. This is why breathing rate stays elevated after you stop exercising.
๐ Comparing Aerobic and Anaerobic
| Feature | Aerobic | Anaerobic (muscles) | Anaerobic (yeast) |
|---|---|---|---|
| Oxygen required? | Yes | No | No |
| ATP yield | ~38 ATP | ~2 ATP | ~2 ATP |
| Products | COโ + HโO | Lactic acid | Ethanol + COโ |
| Location | Mitochondria + cytoplasm | Cytoplasm | Cytoplasm |
| Suitable for | Sustained activity | Short intense bursts | Brewing/baking |
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