List the chemical elements that make up: carbohydrates, fats and proteins.
4.1 Biological molecules
Carbohydrates – the quick‑fuel of the body
Think of carbohydrates as the batteries that power your brain and muscles. They are made up of only three elements:
- Carbon (C)
- Hydrogen (H)
- Oxygen (O)
Fats (Lipids) – the long‑term energy store
Fats are like the long‑term batteries that keep you going when you’re out of quick fuel. They also contain only three elements:
- Carbon (C)
- Hydrogen (H)
- Oxygen (O)
Proteins – the building blocks and repair crew
Proteins are the construction workers of your cells. They’re built from five main elements:
- Carbon (C)
- Hydrogen (H)
- Oxygen (O)
- Nitrogen (N)
- Sulphur (S) – only in some proteins (e.g., cysteine, methionine)
| 📌 Exam Tip |
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When you’re marking a question, remember that carbohydrates, fats and proteins all contain C, H and O. The key difference is that proteins also have N (and sometimes S). Write the elements in a tidy list to show you’ve thought about the composition. 💡 Tip: Use a quick mnemonic: Carbs, Fats, Proteins – CH2O, CH2O, CH2O + N (+ S). |
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