EUKARYOTIC PLASMA MEMBRANE

 PLASMA MEMBRANE

·       Plasma membrane is also called as Cytoplasmic membrane or Cell membrane.

·     The plasma membrane is a semi-permeable membrane that separates the inside of a cell from the outside.

·   In Eukaryotic cells, the Plasma membrane consists of Proteins, Carbohydrates and two layers of Phospholipids. These Phospholipids are arranged as bilayer with Hydrophilic head (Water loving) and Hydrophobic tail (Water hating).

·    In 1972, Singer and Nicolson described the structure of the Plasma membrane as the ‘Fluid Mosaic Model’. The reason is that the bi-layer looks like a mosaic and has a semi-fluid nature that allows lateral movement of Proteins within the bilayer.

·    Different types of Lipids such as Cholesterol, may also be found in the Cell membrane and affect its fluidity.

Fluid – Mosaic Model of Plasma membrane

·       The Plasma membranes of cells that specialize in absorption are folded into fingerlike projections called Microvilli. This folding increases the surface area of the Plasma membrane. Such cells are typically found lining the small intestine, the organ that absorbs nutrients from digested food.

Functions of Plasma Membrane

·       Selectively permeable (It allows only selected substances to pass through).

·       Protects the cell from Shocks and Injuries.

·    The fluid nature of the membrane allows the interaction of molecules within the membrane. It is also important for secretion, cell growth and cell division.

·       Transport of molecules (Passive transport and Active transport)

·       Excretion of wastes from cells.