1.5: ipids

Contain carbon,oxygen and hydrogen
Insoluable in water
Soluable in organic solvents
The proportion of oxygen to carbon and hydrogen is lower than in carbohydrates

Oxidised to release energy

Insoluable in water

Slow conductors of heat and when stored below the body surface they help to retain heat

1 glycerol molecule and three fatty acid molecules (hydrocarbon tails)
Each fatty acid forms an ester bond with glycerol through a condensation reaction

1. Low mass to energy ratio-good storage molecules because energy can be stored in a small volume

2. Large non polar molecules which are insoluble in water- doesn’t affect water potential of cells or osmosis

3. High ratio of hydrogen to oxygen atoms-when oxidised they release water providing an important source of water especially for organisms living in deserts

4. High ratio of carbon-hydrogen energy storing bonds-good source of energy

Same as a triglyceride except that one of the fatty acid tails is replaced by a phosphate group
Hydrophilic head and hydrophobic tail

1.Hydrophilic head and the hydrophobic tail- in an aqueous environment they form a bilayer within cell-surface membranes. A hydrophobic barrier is formed between the inside and the outside of the cells.
2. Hydrophilic phosphate heads- help to hold at the surface of the cell-surface membrane
3. Phospholipid structure- allows them to form glycolipids by combining with carbohydrates within the cell surface membrane.

1. Take 2cm3 of the sample being tested and add 5cm3 of ethanol

2. Shake the tube throughly to dissolve any lipid in the sample

3. Add 5cm3 water and shake gently

4. A milky-white emulsion represents the presence of a lipid

5. As a control repeat the method using water instead of the sample and it should remain clear