Ultra Structure of Plasma Membrane

The structure of plasma membrane of Bacteria, its layers, transport mechanism.

1. ULTRA STRUCTURE OF PLASMA MEMBRANE Submitted To:- Submitted By:- Ms. DEVKI SONAL SINGH (18BMIN001)

2. Outermost / Cell membrane. Thickness is about 5-8 nm. Selectively permeable. Serves as outer boundary. Made up of Phospholipids, Proteins, and conjugated molecules. Separate and protect cell from external environment. What is PLASMA MEMBRANE?

3. Proposed in 1972, by Singer and Nicolson. “Cell membrane is lipid bilayer in which proteins are partially embedded like floating icebergs in sea.” It describes the plasma membrane as a flexible boundary of a cell. The phospholipids move within the membrane. FLUID MOSAIC MODEL

4. Structure of PLASMA MEMBRANE

5. The plasma membrane is composed of two layers of phospholipids back-to-back. It consists of some components:- Phospholipids Peripheral (extrinsic) protein Integral (Intrinsic) protein Cholesterol Glycoprotein Glycolipid

6. Phospholipids are lipids with a phosphate attached to them. They have fatty acid tails (hydrophobic) and phosphate group head (hydrophilic) arranged as a bilayer. Phospholipids, glycolipids, cholesterol are amphipathic lipids containing hydrophobic and hydrophilic ends. PHOSPHOLIPIDS

7. Also called as Peripheral Protein. Proteins loosely associated with membrane surface. Located entirely outside of the lipid bilayer. Either on the extracellular or cytoplasmic surface. Also called as Integral Protein. Tightly bound to lipid layer. Provides channel for the water-soluble substances EXTRINSIC MEMBRANE PROTEIN INTRINSIC MEMBRANE PROTEIN

8. Transport proteins allow needed substances or waste materials to move through the plasma membrane. Transport by CELL MEMBRANE

9. ACTIVE TRANSPORT PASSIVE TRANSPORT Diffusion against concentration gradient. Low  High Uses a protein pump. Requires ATP. SIMPLE diffusion Diffusion of non-polar, hydrophobic molecules (lipids) High  Low FACILIATED diffusion Diffusion of polar, hydrophilic molecules. Through a protein channel. High  Low

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