Lipids

Hydrophobic

Non-polar so is repelled by water

What is myelin

is a lipid and as it is non polar it prevents the passage of hydrophilic ions (eg Na & K and others dissolved in water) and this results in insulation and faster conduction down nerve fibers.

Use of Oil

fur /feathers of animals whereas plants use wax.

phospholipid bilayers

They have a hydrophilic (polar) [water loving] head and a hydrophobic (non polar) [water hating] tail, this allows them to form ________ which make up cell membranes.

What does saturated mean

every carbon is joined by single bonds

What does unsaturated mean

at least one C=C bond

Polyunsaturated

the term for Multiple C=C bonds

How do they bond together

By condensation reactions

Hydrophobic

no osmotic effect on cell

What elements make up lipids

Carbon hydrogen and oxygen

What functions do they have

-

Waterproofing, energy stores, Insulation

What two molecules in lipids

Fatty acids and glycerol

What type of fats are plant fats

Unsaturated

What effect does the C=C bond have

Bends the molecule so they can't pack closely together making most of these oils

Triglyceride

A molecule made up of a glycerol and 3 fatty acids

How do triglycerides bond

By condensation reactions forming ester bond

Why is it useful lipids are hydrophobic

As they have no osmotic effect on the cell

What makes them good at waterproofing

Hydrophobic as the lipid tail is non polar and water is polar

What makes lipids good heat insulators

Poor conductors of heat
Fat reserves have poor blood supplies so little heat gets released to the fat

What is different about a phospholipid

One fatty acid substituted for a phosphate group

Why is the membrane fluid

Some of the fatty acid chains may be unsaturated creating kinks preventing tight packing resulting in fluid like motion

How is the membrane selectively permeable

Due to the polar head an the non polar tail it prevents polar molecules (i.e ions in water) moving through (unless the cell creates special structures to allow this which it can regulate) but lipid soluble ions can pass between the cell and the outside unaffected