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) Artificial membrane models for studies...

Aggregates, tethering, tight junctions **Protein Confinement**: 7. Membrane Protein Organization Cell cortex and spectrin network (e.g., in red blood cells) Artificial membrane models for studies **Liposomes**: Separation of dif environments SDS, Triton used to study integral membrane Adhesion & fixation 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 Photobleaching)**: Signal reception and transmission 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 **Fluidity affecting Factors**: 5. Membrane Dynamics hydrophilic (non polar) regions in the same head hydrophobic hydrocarbon tail to water Cholesterol content molecule), bilayer formation **Phospholipids** (Main components of cell membrane ) Temperature effects Cellular Biology - Types: Phosphatidylethanolamine, Phosphatidylcholine, phosphatidylserine (in the Plasma Membrane inner layer), Sphingomyelin Outer leaflet: Phosphatidylcholine, Sphingomyelin, Glycolipids Structure Stabilizes membranes by intercalating between phospholipids (OH= hydroxyl) **Lipids (40%)** **Cholesterol** Inner leaflet: Phosphatidylethanolamine, Prevents excessive fluidity **Leaflet (couche) Composition**: Phosphatidylserine Found on the Surface Cholesterol in both leaflets of All Eukaryotic Plasma Membranes **Glycolipids** Converting extracellular signals into 4. Membrane Asymmetry Responsible for cell signaling & recognition intracellular ones, specifically through negatively charged Types: Transmembrane (1 to 5), Lipid-linked (1, 7, phospholipids in the cytosolic face of the 8), Peripheral proteins (9 and 10) plasma membrane **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 **Carbohydrates (8%)** **Glycocalyx**: 3. Membrane Structure 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