Unit 2 - Lipids

Hydrogen, oxygen, carbon

NON polar As electrons in the outer shell, that form bonds, are more evenly distributed that polar molecules There are no positive or negative areas

Lipids have no areas or positive and negative so are non polar Water is polar Polar and non polar do not mix as the polar has distinct negative positive areas

Macromolecules

1 glycerol, 3 fatty acids Glycerol is an alcohol Fatty acids are carboxylic acids (-COOH)

Both glycerol and fatty acids have a hydroxyl OH group They interact, leading to formation of three water molecules and bonds between the fatty acids and the glycerol These are ester bonds It is a condensation reaction

C=oo

Causes the molecule to kink or bend So the molecule cannot pack so closely together So are liquid at room temp, nots solid

Modified triglycerides, as they contain phosphorous as well as c h and o

Inorganic phosphate ions po4 3-

Soluble in water as they have extra electrons

A non polar end (tail), the fatty acid chains And a charged end, (head) which is the phosphate group Tails are hydrophobic heads are hydrophilic

Due to the hydrophilic heads and hydrophobic tails of phospholipids, they will form a layer on the surface of water with the heads inside and the tails sticking out Short for surface active agents

Phospholipids can separate aqueous environment in which cells usually exist, from the aqueous cytosol in cells.

In the liver and intestines

Membrane formation Creation of hydrophobic barriers Hormone production Electrical insulation, needed for impulse transmission in the body nervous system Waterproofing eg plant leaves

Thermal insulation to reduce heat loss Cushioning of vital organs Buoyancy of aquatic animals

Emulsion test 1) mix sample with ethanol 2) add to water and then shake 3) if a white emulsion forms, it is a positive test and lipids are present If clear the negative