Lecture 4 - Plasma Membrane.docx

**Lecture 4: Plasma Membrane** **Plasma Membrane** - also called the ***cell membrane*** - **Main Function**: - Surround every cell (integrity of the cell) - Controls movement of molecules into and out of cell - Ions, waste, nutrients - Cell-Cell communication...

**Lecture 4: Plasma Membrane** **Plasma Membrane** - also called the ***cell membrane*** - **Main Function**: - Surround every cell (integrity of the cell) - Controls movement of molecules into and out of cell - Ions, waste, nutrients - Cell-Cell communication - **Description:** Spherical cell - **Composed of:** - Thin bilayer composed of proteins and lipids (some carbs). **lipids** called **(Phospholipid molecules)** - Bilayer = Head and Tail (head facing outside, tail facing inside) - The Polar heads = Hydrophilic, negatively charged - The Non-polar tails = Hydrophobic, uncharged; fatty chain tails - Hydrophobic: Water Fearing - Hydrophilic: Water Loving - Why do they hate and love water? - Due to the properties of water (H2O) Oxygen likes to keep electrons in its own orbit = charged, Hydrogen bad at keeping electrons in its orbit = uncharged. Charged layers attract/love water - Phospholipids = twirl, vibrate, move around within their half, exchange places - Never go from ICF to ECF side unless unhealthy - **Function of Bilayer**: to separate Extracellular & Intracellular compartments - Intracellular compartments: Inside the cell (water) - Extracellular compartments: Outside the cell (water) - Fluid Mosaic Model - Fluid: moving, not rigid, Mosaic: not uniform - PL 50x more than proteins, Proteins = more than Half of membrane mass Protein Types (within the Plasma Membrane) - Come in different shapes and sizes due to different purposes / functions - Protein Types - Channels: - Carrier Modules: transfer of specific molecules (glucose) - Docking marker acceptors: - Membrane bound enzymes: - Receptors: signal - Cell adhesion molecules (CAMs):