PLASMA (CELL) MEMBRANE

Short note on cell membrane.

Cell membrane

The outer surface of every cell is enclosed by an extremely thin, delicate limiting membrane that separates the cytoplasm from its external environment, is called plasma membrane, cell membrane or plasmalemma.

Chemistry & structure: Phospholipids, chemicals & proteins.

Thickness: 7.5-10 nm.

Composition:

• Lipids
• Phospholipids

• Head: hydrophilic
• Tail: hydrophobic
• Form lipid bilayer

• Cholesterol
• Glycolipids

§         Carbohydrate component

§         Part of glycocalyx

• Protein

§         Integral membrane proteins

§         Peripheral membrane proteins

§         Some serve as enzymes, ion channels or receptors

§         Glycoproteins

Function of plasma membrane
 

·        Selectively permeable barriern

§         Nutrient in

§         Waste out
 

·        Communication

·        Intercellular connections

·        Physical barrier