Download Biological Significance of Lipids

Lipids in cells &
Tissues
Lipids :are macromolecules
composed of C, H and O, and other
atoms as Phosphor. They are
water-insoluble but dissolve in
organic solvents as alcohol and
acetone.
Biological Significance of Lipids:
1- Component of cellular membranes.
2- Source of energy and contains more energy than
carbohydrates.
3- Some hormones are lipid-derivatives.
4- Work as heat insulator, and shock absorbent.
Fatty acids + Alcohols = Lipids
Lipids
derived Lipids
Steroids
compound Lipids
Phospholipids
Simple Lipids
Neutral fats
Waxes
Neutral fats: Most lipids
in cell and in general are
neutral fats. They are
composed of 1 molecule of
glycerol and 3 molecules of
fatty acids.
Neutral fats can be either
saturated fats like butter,
or unsaturated like oils.
Waxes:
similar to neutral fats structure but instead of
glycerol they contains other larger alcohols.
Phospholipids:
Has 1 phosphate group (PO4) instead of
one fatty acid. Found in all cells as
component of cellular membranes
Steroids:
differs from other lipids in that it contains a steroid
nucleus (4 cyclic rings, 3 of which are 6 C and 1 is 5 C
ring). e.g. sex hormones and cholesterol.
Lipids in tissues:
Muscle
Liver
Detection of Cholesterol in samples: milk, butter,
margarine, olive and corn oil
1- Mark 6 tubes from 1-6, to each tube add 0.5 ml of acidic
potassium sulfate KHSO4. Add 5 drops of each sample to each tube,
then add 2.5 ml of KHSO4 Heat over flame for few minutes.
2- Mark 6 new tubes from 1-6, to each tube add 2 ml of sample
+ 1 ml chloroform + 1 ml of acetic anhydride (CH3CO)2O + 2 ml of
conc. Sulfuric acid (very carefully).