Biology: Topic 2: Macromolecules: Lipids

What are macromolecules?

Very large, complex molecules built from multiple, repeating units (monomers) added together. are polymers (long molecule consisting of many similar or identical building blocks linked by covalent bonds). Carbohydrates, nucleic acids and proteins

What are the 3 types of lipids:

1. Triglycerides- fats (and oils)

2. Phospholipids

3. Steroids

Hydrophobic - mostly hydrogen and carbon

Saturated vs unsaturated fatty acids

Saturated fatty acids have no double bonds between carbons. Solid at room temperature- butter

Unsaturated fatty acids have one or more double bonds. Liquid at room temperature- oil. Unsaturated fatty acids can't pack closely enough due to the double bonds to create strong enough bonds to keep it solid at room temp.

Triglycerides (fats and oils)

- Formed from 1 glycerol (3 carbon molecule) and 3 fatty acid molecules

- fatty acid molecules are long hydrocarbon tails (C and H), non polar, hydrophobic, different fatty acids have different length tails

Function of lipids

Energy storage, insulation, signalling, membrane structure

Phospholipids

• two fatty acids and a phosphate attached to glycerol

• Fatty acid tails are hydrophobic

• Phosphate group and its attachments are hydrophilic

• Self assemble into bilayer - fundamental structure of cell membranes

Steroids

• characterised by four carbon rings

• Cholesterol is a component in animal cell membranes and a precursor from which other steroids are synthesised