1. Lipids and Membrane Structure

2. Content This section of the syllabus includes:
Biological functions of lipids
Triglycerides
Phosphoglycerides; formation of bilayers

3. Describe the structure and function of Triglycerides
A triglyceride is made when 3 fatty acids form ester bonds with glycerol.
Their main function is to store and supply energy for metabolism.

4. The Hydrolysis of Triglycerides
Triglycerides are hydrolysed with high pressured steam to yield fatty acids.
These are then neutralised with an alkali eg. NaOH to give soap and water.

5. How much do you remember?
1.What are triglycerides made from?
2.Name one function of a triglyceride:
3.When triglycerides are hydrolysed what do they yield?

6. The Solubility of Triglycerides
As lipids, triglycerides are soluble in non- polar organic substances such as chloroform and benzene but in soluble in water.
They are soluble in non-polar substances which are describe as hydrophobic or lipophillic.
Triglycerides have a high viscosity.

7. Phosphoglycerides
Phosphoglycerides are used in the body to make cell membranes and make good emulsifiers.
All phospholipids have polar areas which are hydrophillic or hydrophobic.
Bimolecular layers are formed from phosphoglycerides as shown:

8. Phosphoglyceride membrane bilayer

9. Bimolecular Layer
This type of membrane is useful as it regulates the movement of substances across into the cell.

10. Quick quiz Kishan: Name two uses of phosphoglycerides:
Matt K: Give an example of an alkali used to neutralise fatty acids:
Matt W (if here x): What are triglycerides soluble in?
Tim: Name the main function of the membrane bilayer:

11. Final details
Lipids (CH2)n are essentially a concentrated energy store of carbon and hydrogen.
Made up of C and H, lipids when broken down produce twice as much energy as the equivalent mass of carbohydrates.

12. Cont.
Carbohydrates (CH20)n are made up of partly oxidised carbon and hydrogen units allowing `instant access`to energy.
When lipids are broken down (metabolised) they are released slowly. The energy from the C-H bonds in transferrred to smaller molcules.