The_lipid_bilayer - Topic 2 Cell membranes Reading Chapter...

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Topic 2 – Cell membranes Reading Chapter 5 Objectives Functions of cell membranes BIO 1140 – SLIDE 1 The fluid mosaic model The lipid bilayer – phospholipids, glycolipids and sterols Properties of the lipid bilayer Membrane proteins – the ‘mosaic’ in the model Solute movements across membranes http:/ www.nikonsmal world.com/gal ery/year/2006/id/751 Functions of cell membranes – an overview Fluid mosaic model Fluid lipid molecules in which proteins are embedded and freely floating BIO 1140 – SLIDE 2 freely floating. Functions 1. Define boundaries; selectively permeable barrier 2. Localisation and organisation Scaffold for biochemical activities (enzymes) e.g. mitochondria Fig. 7-2, Becker et al. 2009 3. Regulation of solute transport In and out of cell and/or organelles Uphill or downhill e.g. Na + ,K + -ATPase 4. Responses to external signals BIO 1140 – SLIDE 3 Receptors and signal transduction e.g. ß-adrenoreceptor 5. Cell-to-cell communication Recognition, adhesion, exchange of materials Gap junctions, plasmodesmata Fig. 7-2, Becker et al. 2009 - permeable barrier - also control what goes in and out through protein functions - - membrane contains special receptor molecules - recognition and attachment - passageway from the cytoplasm of one cell to cytoplasm of another - gap junctions - permanent opening between two -
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Plasma membrane of Schwann cell (myelin sheath) 18% protein 82% lipid BIO 1140 – SLIDE 4 Figs. 6.8, 33.5 Inner mitochondrial membrane 76% protein 24% lipid Membrane structure Fluid mosaic model Lipid-protein assembly in which components are held together in a thin sheet by non-covalent bonds Two fluid lipid layers – structural backbone, permeability barrier Mosaic of proteins – unique complement responsible for specific functions ~10 nm thick BIO 1140 – SLIDE 5 Fig. 5.1 Membrane structure Fluid mosaic model Lipid-protein assembly in which components are held together in a thin sheet by non-covalent bonds Two fluid lipid layers – structural backbone, permeability barrier Mosaic of proteins – unique complement responsible for specific functions ~10 nm thick BIO 1140 – SLIDE 6 Fig. 5.2 - can have protein rich membrane or lipid rich membrane - ex. lipid rich - membrane of Schwann cell (myelin sheath) - membranes can be thought of as assemblies held together by non-covalent bonds - proteins may be free to move around in the lipid bilayer - lipid bilayer - basic permeability barrier Midterm on Saturday, Jan. 28 - 10:30am 20 MC!
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Membrane structure Fluid mosaic model Lipid-protein assembly in which components are held together in a thin sheet by non-covalent bonds Two fluid lipid layers – structural backbone, permeability barrier Mosaic of proteins – unique complement responsible for specific functions
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This note was uploaded on 03/26/2012 for the course BIO 1140 taught by Professor Fenwick during the Winter '07 term at University of Ottawa.

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The_lipid_bilayer - Topic 2 Cell membranes Reading Chapter...

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