Date Chapter 7 Membrane Structure Function Membrane structure
Date ______ Chapter 7 - Membrane Structure & Function
Membrane structure, I l l Selective permeability Amphipathic l l hydrophobic & hydrophilic regions Singer-Nicolson: l fluid mosaic model
What structure looks familiar?
Membrane structure, II l l l Phospholipids l membrane fluidity Cholesterol l membrane stabilization “Mosaic” Structure l Integral proteins l l Peripheral proteins l l transmembrane proteins surface of membrane Membrane carbohydrates l l l cell to cell recognition oligosaccharides (cell markers) glycolipids; glycoproteins
What looks familiar?
Membrane structure, III l Membrane protein function: l l l Transport Enzymatic activity Signal transduction Intercellular joining Cell-cell recognition ECM attachment
What looks familiar?
Membrane traffic l Diffusion l l l Concentration gradient Passive transport l l tendency of any molecule to spread out into available space diffusion of a substance across a biological membrane Osmosis l the diffusion of water across a selectively permeable membrane
Seen on “U-tube” Extremely important. Let’s model this.
Water balance in cells l Osmoregulation l l Hypertonic l l lower concentration of solutes Isotonic l l higher concentration of solutes Hypotonic l l control of water balance equal concentrations of solutes Cells with Walls: l l l Turgid (very firm) Flaccid (limp) Plasmolysis~ plasma membrane pulls away from cell wall
Hippo and the hyper person
Specialized Transport l l Transport proteins Facilitated diffusion l l passage of molecules and ions with transport proteins across a membrane down the concentration gradient Active transport l movement of a substance against its concentration gradient with the help of cellular energy
How to get into the club…
Types of Active Transport l l Sodium-potassium pump Exocytosis l l secretion of macromolecules by the fusion of vesicles with the plasma membrane Endocytosis l import of macromolecules by forming new vesicles with the plasma membrane l phagocytosis pinocytosis receptor-mediated endocytosis (ligands) l l
Wheel on the bus go…
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