BRAINCAKEThe Nature of Lipids
Lipids are a varied group of organic compounds that contain carbon, hydrogen and oxygen. Compared with carbohydrates they contain a much smaller proportion of oxygen and a large proportion of hydrogen, mostly in long hydrocarbon chains.
The key feature of lipids is that they are insoluble in water but soluble in organic solvents such as ethanol. Their long hydrocarbon chains are non-polar, so they cannot form hydrogen bonds with water: they are hydrophobic.
Lipids are large molecules, but they are not polymers, because they are not built from a chain of repeating monomers.
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Key terms in this lesson
- steroid
- A lipid with a structure based on four fused carbon rings; examples include cholesterol and steroid hormones such as testosterone.
More in Biological Molecules
- Starch
- Test for Starch
- Glycogen
- Cellulose
- Fatty Acids and Glycerol
- Triglycerides
- Phospholipids
- Unit Membrane
All 25 lessons in Biological Molecules · All Edexcel AS-level Biology topics