M1_membranes2010

M1_membranes2010 - Human Physiology BMS 653 II. Nerve and...

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LC 2F. Membrane and Membrane Transport LC 2F. Membrane and Membrane Transport J. Michael O’Donnell, PhD J. Michael O’Donnell, PhD Department of Physiology and Biophysics Department of Physiology and Biophysics COMRB, Room 1115 COMRB, Room 1115 odonnell@uic.edu odonnell@uic.edu 312-413-8276 312-413-8276 Office Hours: Email for Appt. Office Hours: Email for Appt. Text Book: Physiology, Berne and Levy; 6 Text Book: Physiology, Berne and Levy; 6 th th edition edition Reading material: Chapters 1, 2, 5, and 6 Reading material: Chapters 1, 2, 5, and 6 August 17, 2010 August 17, 2010 Human Physiology BMS 653 II. Nerve and Muscle
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Today’s objectives: Today’s objectives: 1) Describe the general composition of a cell membrane 2) Define and manipulate variables affecting diffusion 3) Define and manipulate variables affecting osmosis 4) Calculate cell volume changes associated with changes in tonicity 5) Differentiate between facilitated diffusion, primary active transport, and secondary active transport
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water phospholipids hydrophilic hydrophobic Phosphatidlyethanolamine Fatty acyl chain
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Fluid mosaic model MEMBRANE COMPOSITION (1) Lipids (a) phospholipids: Choline-containing -lecithins (phosphatidylcholine) -sphingomyelins Amino-phospholipids -phophatidylserine -phophatidylethnaolamine Others -phoshatidylglycerol -phoshatidylinositol -cardiolipin (b) Cholesterol adds rigidity (c) Glycolipids carbohydrates protrude from surface Non-saturated lipids add fluidity to the membrane. Cholesterol is a nonpolar molecule that stabilizes the packing of lipids and decreases membrane fluidity Membrane: lipids, proteins, and carbohydrates
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MEMBRANE COMPOSITION con’t (2) Membrane proteins (a) integral proteins transmembrane protein span lipid bilayer (b) Lipid (fatty acid) anchored proteins protein covalently attached to embeded lipid (c) peripheral proteins bind to polar head group of membrane bind to integral proteins bind to peripheral proteins (d) Glycoproteins carbohydrates protrude from protein Membrane Protein Lipid Carbohydrate Plasma Membrane 46 46 8 Mitochondrial (inner) 76 24 0 Myelin (Schwann Cell) 18 79 3 Percent % Composition of Various Membranes Percent % Composition of Various Membranes
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One main function of the plasma membrane is as a permeability barrier. It It is a selective membrane. Those substances that are lipid soluble are free to is a selective membrane. Those substances that are lipid soluble are free to diffuse, others must be transported across the membrane. diffuse, others must be transported across the membrane. Lipid soluble (ethanol O2 and CO2) Lipid insoluble (solutes: ions, glucose, amino acids) Transport Across Plasma Membrane Transport Across Plasma Membrane Let’s review… Let’s review… Mechanisms of Transport Across Membrane Mechanisms of Transport Across Membrane 1. Simple diffusion of solutes 1. Simple diffusion of solutes 2. Diffusion of water (osmosis and aquaporins) 2. Diffusion of water (osmosis and aquaporins) 2. Carrier mediated solute transporters 2. Carrier mediated solute transporters 3. Endocytosis and exocytosis 3. Endocytosis and exocytosis
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M1_membranes2010 - Human Physiology BMS 653 II. Nerve and...

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