Triglycerides

3. 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.

4. Fatty acid Glycerol Fatty acid Phosphate group Phospholipids are Diglycerides

5. Phospholipids OR

6. POLAR

7. Polar phosphate head (hydrophilic) Hydrophobic fatty acid (lipid) tails Phospholipids The phosphate –containing end of the phospholipid molecule is soluble in water, while the hydrophobic fatty acid tails orientate themselves in positions away from a watery medium The bipolar nature of phospholipids allows these molecules to form bilayers that form a major component of cell membranes

9. PHOSPHOLIPID BILAYER water phospholipid bilayer of cell membrane water cholesterol stabilising the membrane Cholesterol molecules are located between the tails of the phospholipid molecules where they serve to stabilise the membrane These cholesterol molecules are also classed as LIPIDS although they belong to a very different sub - group known as STEROIDS

11. CHALLENGE: Draw this in your books!

12. Summary of Biochemistry of lipids 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.