Biomembranes

different type of bio membranes

1. BIOMEMBRANES 1

2. DEFINITION Biological membranes are thin, flexible surfaces separating cells and cell compartments from their environments 2

3. ORGANELLES CONTAINING MEMBERANE Lysosomes Golgi bodies M itochondria N ucleus 3

4. FLUID MOSAIC MODEL 4

5. COMPONENTS Components of membrane are: Proteins lipids Carbohydrates 5

6. PROTEINS Two basic types of membrane proteins: Integral (Intrinsic) proteins Peripheral (extrinsic) proteins 6

7. INTEGRAL (INTRINSIC) PROTEINS They are embedded in hydrophobic core of lipid bilayer For example : Transmembrane proteins are exposed on both sides of the membrane FUNCTION: Anchorage Transport 7

8. THREE GENERAL CLASSES OF TRANSPORT SYSTEMS 8

9. PERIPHERAL (EXTRINSIC) PROTEINS Peripheral membrane proteins are proteins that adhere outside the biological membrane These molecules attach to integral membrane proteins, or penetrate the peripheral regions of the lipid bilayer FUNCTION: Cell-to-cell interaction Cell signaling 9

10. MANY FUNCTIONS OF MEMBRANE PROTEINS Outside Plasma membrane Inside Transporter Cell surface receptor Enzyme activity Cell surface identity marker Attachment to the cytoskeleton Cell adhesion 10

11. LIPIDS Lipids in membranes are Amphipathic Orientation of Amphipathic compounds (Lipids) in aqueous solution is to prevent Hydrophobic region coming into contact with water molecules Major lipids in biological membranes are : Phospholipids Glycolipids Cholesterol 11

12. PHOSPHOLIPIDS Phospholipid is made up of : Two Non-polar (Hydrophobic) fatty acid chains: Tails One polar (Hydrophilic) group: Head 12

13. Phospholipid molecules are orientated to form: micelle lipid bilayer liposome 13

14. PHOSPHOLIPID 14

15. CHEMICAL NATURE OF PHOSPHOLIPIDS 15

16. GLYCOLIPIDS Glycolipids are lipids that form part of the plasma membrane They have a short carbohydrate chain covalently attached and this is exposed on the outer surface of the  cell Function: Communicative or cellular recognition 16

17. CHOLESTEROL It is a steroid that is amphipathic in nature Function: Provide stability Maintain the fluidity Bilayer stronger Bilayer flexible 17

18. CARBOHYDRATES Carbohydrates covalently linked to proteins (glycoproteins) or lipids (glycolipids) are also a part of cell membranes FUNCTION: cell-cell recognition Basis for rejection of foreign cells by immune system 18

19. GLYCOCALYX Entire surface of cell membrane contain carbohydrate coat called glycocalyx Function: Provide negative charge to the membrane Provide attachment between the cells 19

20. FUNCTION OF CELL MEMBRANE The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of  cells The basic function of the cell membrane is to protect the  cell from its surroundings 20

21. IMPORTANT FEATURES Selective permeability Fluidity 21

22. Thank you 22