Cellular Biology - Plasma Membrane Structure PDF

Aggregates, tethering, tight junctions **Protein Confinement**: 7. Membrane Protein Organization Cell cortex and spectrin network (e.g., in red blood cells)...

Aggregates, tethering, tight junctions **Protein Confinement**: 7. Membrane Protein Organization Cell cortex and spectrin network (e.g., in red blood cells) Separation of dif environments Artificial membrane models for studies **Liposomes**: Adhesion & fixation SDS, Triton used to study integral membrane proteins, they can be isolated from the lipid bilayer by solubilization using **Detergents**: 6. Membrane Tools & Methodologies Force transmission to cytoskeleton detergents 1. Plasma Membrane Overview **Functions**: Exchange & transport Measures protein/lipid mobility **FRAP (Fluorescence Recovery After Signal reception and transmission Photobleaching)**: Fusion protein technique with GFP Cellular recognition (cells identify and interact with each other or with molecules) Chain length of hydrocarbon tails Degree of saturation (unsaturated = more fluid) Amphipathic (hydrophobic (polar) and Composed of 2 fatty acids attached to a polar Closed structure to avoid the exposure of hydrophilic (non polar) regions in the same **Fluidity affecting Factors**: 5. Membrane Dynamics molecule), bilayer formation head hydrophobic hydrocarbon tail to water Cholesterol content **Phospholipids** (Main components of cell membrane ) Temperature effects Cellular Biology - Types: Phosphatidylethanolamine, Phosphatidylcholine, phosphatidylserine (in the Plasma Membrane inner layer), Sphingomyelin Outer leaflet: Phosphatidylcholine, Structure Stabilizes membranes by intercalating between phospholipids (OH= hydroxyl) Sphingomyelin, Glycolipids **Lipids (40%)** **Cholesterol** Prevents excessive fluidity Inner leaflet: Phosphatidylethanolamine, **Leaflet (couche) Composition**: Phosphatidylserine Found on the Surface of All Eukaryotic Plasma Membranes Cholesterol in both leaflets **Glycolipids** 4. Membrane Asymmetry Responsible for cell signaling & recognition Converting extracellular signals into intracellular ones, specifically through negatively charged phospholipids in the cytosolic face of the Types: Transmembrane (1 to 5), Lipid-linked (1, 7, plasma membrane 8), Peripheral proteins (9 and 10) **Functional Importance**: 2. Membrane Composition Functions: Enzymes, transporters, receptors, distinguish Cell death (apoptosis) **Membrane proteins**: adhesion proteins **Proteins (52%)** Amphipathic nature, alpha-helices, or beta- Membrane as a dynamic and heterogeneous barrels structure (different phospholipids, proteins, and complex sugars) **Protein diffusion**: Lateral diffusion (FRAP method) **Fluid Mosaic Model** fluid because the phospholipids and Protects cells, aids in recognition (e.g., blood proteins can move within the plane of the group antigens) membrane 3. Membrane Structure **Carbohydrates (8%)** **Glycocalyx**: short chains of sugars (oligosaccharides) linked spontaneous bilayer formation to them - glycoproteins. Others have longer Movement types: lateral diffusion, rotation, polysaccharide chains - proteoglycans 2D fluidity **Lipid Bilayer** flexion, rare flip-flop Trilamellar structure