Topic 3 - Membrane Permeability + ATP-Dependant Pumps PDF

🍔 Topic 3 - Membrane Permeability + ATP-Dependant Pumps Phys&Pharm - Group work session 3 - Transporters - 2023.docx What is the function of the phospholipid bilayer Communication: control flow of inform...

🍔 Topic 3 - Membrane Permeability + ATP-Dependant Pumps Phys&Pharm - Group work session 3 - Transporters - 2023.docx What is the function of the phospholipid bilayer Communication: control flow of information between cells + environment. Reception – response: recognition of signalling molecules Selectivity: Control of flow/transport of substances Mitochondrial membrane - energy conservation by oxidative phosphorylation What is the Membrane Composition Topic 3 - Membrane Permeability + ATP-Dependant Pumps 1  Phospholipids - Amphipathic molecules (glycerol attached to two hydrophobic fatty acid chains + phosphate hydrophilic head group). Fatty acids poorly soluble in water. 40% lipid, 60% protein, 1-10% carbohydrate What is the Lipid Mosaic Model Topic 3 - Membrane Permeability + ATP-Dependant Pumps 2  Van der Walls forces allow bilayer formation between hydrophobic tails → Stability lipid bilayers have low permeability to ions and polar molecules Name 2 types of membrane proteins Integral Proteins Peripheral Proteins How do Carbohydrates play a role in Membrane Composition Carbohydrates make an Exterior surface bound to lipids and proteins Allow cell recognition Membrane proteins modified with a carbohydrate group to form glycoproteins. Glycolipids are modified lipids with a carbohydrate group instead of a phosphate group. What is the Glycocalyx Glycocalyx is highly hydrophilic Topic 3 - Membrane Permeability + ATP-Dependant Pumps 3  What are the 3 factors which influence Cell Membrane Fluidity Temperature: Cold: Phospholipids are closer together. Hot: Phospholipids move farther apart. Cholesterol: Prevents excessive separation or tight packing of phospholipids. Maintains fluidity Saturated and Unsaturated Fatty Acids: Saturated Fatty Acids: Straight chains - single bonds. Pack tightly. Unsaturated Fatty Acids: double bonds chains Create kinks (bends in fatty acid chain) Harder to pack tightly. Erythrocyte Membrane Model Biconcave disc – 120 days of lifespan Specialised cytoskeleton (flexibility and stability) Lipids + Proteins (Spectrin + actin) Topic 3 - Membrane Permeability + ATP-Dependant Pumps 4  Band 3, Ankyrin, Protein 4.2, Spectrin: What TF IS Band 3 (EMM) Band 3: Cl-/HCO3- exchanger. Integral protein. Links to protein 4.2 and ankyrin. Ankyrin (EMM) Ankyrin (protein) Links integral membrane proteins to the Spectrin-actin cytoskeleton. Protein 4.2 (EMM) ATP-binding protein. May regulate the association of band 3 with ankyrin. Spectrin (EMM) Crosslinks with actin. Forms the spectrin-actin cytoskeleton, which is linked with the integral membrane proteins through Ankyrin Topic 3 - Membrane Permeability + ATP-Dependant Pumps 5  What is Hereditary spherocytosis Spectrin protein is depleted to