Topic 3 - Membrane Permeability + ATP-Dependant Pumps PDF

Summary

This document discusses membrane permeability and ATP-dependent pumps. It covers topics such as the function of the phospholipid bilayer, membrane composition, and the lipid mosaic model. The document also explores different types of membrane proteins, carbohydrates' role in membrane composition, and factors influencing membrane fluidity.

Full Transcript

🍔 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

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