Triglycerides

• The glycerol molecule is always the same.

• The differences in the properties of fats and oils comes from over 70 types of fatty acids.

GlycerolFatty acid

Fatty acid

Phosphate group

OR

hydrophilic phosphategroup

Gl ycero l

Fatty acid

Fatty acid

Phosphate

hydrophobic tails

POLAR

Polar phosphate head(hydrophilic)

Hydrophobic fatty acid(lipid) tails

The phosphate –containing endof the phospholipid molecule is

soluble in water, while thehydrophobic fatty acid tails

orientate themselves in positionsaway from a watery medium

The bipolar nature ofphospholipids allows these

molecules to form bilayers thatform a major component

of cell membranes

PHOSPHOLIPIDBILAYER

water

water

phospholipidbilayer of cellmembrane

cholesterol stabilisingthe membrane

Cholesterol moleculesare located between thetails of the phospholipidmolecules where they serve to stabilise the

membraneThese cholesterol molecules

are also classed as LIPIDSalthough they belong to

a very different sub - groupknown as STEROIDS

CHALLENGE: Draw this in your books!

More detail will follow in the chemistry of life section (3.2.2)

• Fats & oils are made up of carbon, hydrogen and oxygen atoms.• The building blocks (monomers) of fats and oils are glycerol &

fatty acid molecules.• Fats & oils are TRIGLYCERIDES. • Diglycerides form when TWO FATTY ACIDS bond with a glycerol

molecule.• Phospholipids are DIGLYCERIDES.• Phospholipids form when TWO FATTY ACIDS and a PHOSPHATE

group bond to a glycerol molecule.• The phosphate end of the molecule is hydrophilic (water - loving)

and the two fatty acids tails are hydrophobic (water - hating).• Phospholipids are a major structural component of cell

membranes.