all about the membrane lipids and components

1. MEMBRANE LIPIDS

2. INTRO
 Membranes contain a wide diversity of lipids
 All of which are amphipathic; that is, they
contain both hydrophilic and hydrophobic
regions.
 There are three main types of membrane
lipids: phosphoglycerides, sphingolipids, and
cholesterol.

3. Phosphoglycerides
 Called as phospholipids
 Has phosphate group attached to glycerol
backbone and other two carbon atoms linked
to fatty acid chains
 Triglycerides have three fatty acids, but
membrane glycerides have two fatty acid
chains
 The third carbon attached to phosphate group
forms – PHOSPHATIDIC ACID

4.  Further the phosphate group attached to
1. Choline (phosphotidylcholine)
2. Ethanolamine (phosphotidylethanolamine)
3. Serine (phosphotidylserine)
4. Inositol (phosphotidylinositol)
 This forms the water soluble domain – HEAD
GROUP
 At physiological pH – PS and PI – negative
charge
- PE and PC – positive charge

5.  Fatty acid chains – 16-22 carbons
 Contains one saturated and one unsaturated
fattyacyl chain

6. Phospholipids

7. Sphingolipids
 Derivative of sphingosine (amino alcohol)
 Spingosine linked to fatty acid by amino group –
CERAMIDE
 Additional groups are esterified to terminal alcohol
of sphingosine moiety –
if phosphorylcholine – SPHINGOMYELIN
if carbohydrate – glycolipid –
simple sugar – CEREBROSIDE
cluster of sugars – GANGLIOSIDES
 NERVOUS SYSTEM – RICH IN GLYCOLIPID -
GALACTOCEREBROSIDE

8. Sphingolipids

9. Cholestrol
 Abundant in animal cells
 Oriented with their small hydrophilic OH group
toward the membrane surface and remainder
of molecule in lipid bilayer
 Hydrophobic rings are flat and rigid and
interfere with movement of fatty acid tails

10. Cholesterol

11. Nature and importance of
bilayer
 Lipid composition determines the physical
state of membrane and influence activity of
membrane proteins
 Facilitates fusion or budding or membrane
 Has the ability to self assemble – eg.
Liposomes – wall of fluid filled spherical
vesicles