Lipids || CH 06 || Molecular Biology || Grade 09 || National Book Foundation Islamabad || Federal
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6.4 LIPIDS
A group of different types of organic compounds which are all hydrophobic in nature collectively called lipids Hence, lipids are a heterogeneous group of organic compounds which are insoluble in water but soluble in organic solvent such as alcohol, ether etc. Lipids found in
living organisms include fats, oils, waxes and steroids. Imp Question
Molecutes of lipids are composed of C, H and O like carbohydrates. However one gram of lipids contain double amount of energy than carbohydrates because they have relatively more carbon-hydrogen carbohydrates. rat ratio than
Structure of Lipids
Lipids which are mainly made up of fatty acids and glycerol (an Alcohol) are called Acyl glycerides. Fatty acids may be saturated or unsaturated. (Saturated fatty acids have all C-C single bonds and are solid at room temperature 2-g. cheese, butter, ghee etc. Unsaturated fatty acids) have double or triple C-C bonds and are liquid at room temperature e.g. soybean oil, mustard oil, olive oil etc. Most common types of acyl glycerides are tri-acyl glycerides which contains one glycerol and three fatty acids.
Glycerol + 3 fatty acids Tri-acyl glyceride
tay Some lipids are even more complex and have phosphate, nitrogen base along with glycerol and fatty acids e.g. phospholipids and waxes.
Ethana
Some lipids may not have fatty acids in their formula rather they have three ring structure
called steroids e.g. Cholesterol, vitamin D. Try acyl gooup, H- H
ctions of Lipids
H
Lipids are very useful biological molecules and have many important roles in cells and as a whole in bodies of living organisms.
1. Phospholipids and cholesterol are components of plasma membrane structure. 2.
Lipids act as energy stores in fat cells, liver and in blood. One gram of lipids provides 9.1
kcal of energy which is double than carbohydrates or proteins. 3. Many lipids act as Important steroid hormones e.g. testosterone, Aldosterone etc.
4. Some lipids act as insulators against atmospheric heat and cold. . Waxes are used by insects for constructing their hives. 20 5
6. Waxy cuticle of leaves act as protective and waterproof layer to avoid water loss.
7. Some vitamins are lipid in nature e.g. vitamin A, D, E and K. Vitamin D is derived from cholesterol.
Phospholipids in Cell Membrane
Glycerol
Glycerol
Cell
Phospholipid bilayer (Cell membrane)
Steroids and Waxes
Triglycerides
Glycerol + Phosphate + Nitrogen base
Fatty Acids
Cholestero
Fig: 6.6 Structure of different types of lipids
lipid Saturated. F. Aland I fats Single band
21 окт 2024
