1. Lipids

2. Lipids Made up of C, H and O Can exist as fats, oils and waxes
They are insoluble in water
They are a good source of energy
(9 k cal / g)
They are poor conductors of heat
Most fats & oils are triglycerides

3. Lipids Biomolecules that contain fatty acids or a steroid nucleus.
Soluble in organic solvents, but not in water.
Named for the Greek word lipos, which means “fat.”
Extracted from cells using organic solvents.

4. Triglycerides (Neutral Lipids)
Formed by esterification (condensation reaction between 3 fatty acids and glycerol) H C O
Glycerol

5. A saturated fatty acid (no double bonds)
Fatty acids
Carboxyl group (-COOH)
attached to a long non-polar hydrocarbon chain (hydrophobic) H C O
A saturated fatty acid (no double bonds)

6. A monounsaturated fatty acidH
A monounsaturated fatty acid H C O
A polyunsaturated fatty acid

7. Esterification H C O C O H
Fatty acid
Glycerol

8. Esterification H C O C O H
Fatty acid
Glycerol

9. Esterification C H O C O H H O
Fatty acid
Glycerol

10. Esterification C H O C O H
Ester bond H O
water

11. Esterification This happens three times to form a triglyceride
glycerol
fatty acids

12. Phospholipids
One fatty acid can be replaced by a polar phosphate group
hydrophilic
phosphate
glycerol
Hydrophobic fatty acids

13. Classification of Lipids
Simple lipids
Compound lipids (Complex)
Derived lipids

14. Simple lipids A) Natural Lipids The alcohol is glycerol
Oil (liquid at room temperature)
Fat (solid at room temperature)
Natural lipids need 3 F.As. and one molecule of glycerol to form triglycerides + 3 H2O

15. Simple lipids
B) Waxes
Most natural waxes are esters derived from a fatty acid and a long-chain alcohol
Main biological function of waxes: water barrier
Bee waxes are formed by honey bee and formed from Myricyl alcohol and palmitic acid.

16. Wax minimizes water evaporation
Waxes
Most natural waxes are esters derived from a fatty acid and a long-chain alcohol
Cerotic acid
A fatty acid
remove H2O
Myricyl cerotate
Present in beeswax
Myricyl alcohol
Long chain alcohol
Main biological function of waxes: water barrier
Feathers
Wax minimizes wetting
Leaves
Wax minimizes water evaporation

17. Compound lipids F.A + alcohol + other group
Phospholipids (contain phosphate group)
Glycolipids (contain carbohydrates)
Lipoproteins (contain proteins)

18. Derived lipids
Hormones
Steroids

19. Diversity in structure leads to a diversity in biological function
Non-polar lipids (fats) are the principal molecules for energy storage.
Polar lipids (nitrogen and phosphorus containing) are components of biological membranes.
The steroid (class of lipids) (cholesterol) is found in biological membranes and used as a precursor for many hormones, bile and vitamin D
Miscellaneous lipids present only in minor quantities in the cell are involved as light-absorbing pigments (β-carotene, retinal), enzyme cofactors (vitamin K), signal molecules (prostaglandins), and electron carries.

20. Diversity in structure leads to a diversity in biological function
Used as a fuel reserve (when needed)
Provide body with essential fatty acids
Fats under skin (subcutaneous) are used as insulator and protecting and maintaining the body temperature.
Fats provide the protection and fixation of internal organs.
Lipoproteins enter in the formation of cell wall, muscles, mitochondria and microsomes.