PNB Lecture Outline 2

PNB Lecture Outline 2 - PNB 2264 Fall 2008 Kimball Lecture...

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PNB 2264 Fall 2008 Kimball Lecture Outline 2 THE CELL: SELF-REVIEW Review the cytology you learned in Biology 107 using the textbooks (see syllabus for chapters.) CELL MEMBRANE STRUCTURE AND FUNCTION I. Structure of the Cell Membrane : Fig. 3.2. A. Introduction 1. Functions • Regulate things that enter and leave the cell • Detect chemical messengers arriving at the cell surface • Link adjacent cells together by member junctions • Anchors cells to extracellular matrix “fluid-like” 2. Basic structure: Singer-Nicolson fluid mosaic mode • Membrane proteins that float in a sea of lipid 3. Characteristics • Double layer of lipid molecules containing embedded proteins, major membrane lipids are phospholipids. B. Chemistry 1. Primary lipids are phospholipids. • Phospholipids are amphipathic: one end has a charged/polar region (oriented toward the surfaces of the membrane because of their attraction to the polar water molecules) and the remainder of the molecule consists of two long fatty acid chain, which are nonpolar (oriented inside the surface of the membrane because they are hydrophobic) 2. Cholesterol. • Type of lipid called a steroid • Scattered within the hydrophobic regions of the phospholipid bilayer, where it strengthens the membrane and stabilizes it at temperature extremes, increases the membrane’s fluidity • Associates with certain classes of plasma membrane phospholipids and proteins, forming organized clusters that work together to pinch off portions of the plasma membrane to form vesicles that deliver contents to various intracellular organelles 3. Proteins • Complex, diverse molecules composed of chains of smaller molecules called amino acids • Amphipathic: Polar (at surfaces with polar water molecules) amino acid side chains and nonpolar (interior with nonpolar fatty acids) side chains clustered together in a separate region) • Integral Proteins: closely associated with the membrane lipids and cannot be extracted from the membrane without disrupting the lipid bilayer • Peripheral membrane proteins: are NOT amphipathic and DO NOT associate with the nonpolar regions of the lipids in the interior membrane, located at the membrane surface and bound to polar regions of the integral membrane proteins (influence cell shape and motility) 4. Carbohydrates • Provide the cell with energy, composed of two monosaccharide (disaccharide), which involves a dehydration reactions that link the two monosaccharide together, glucose=most abundant
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PNB Lecture Outline 2 - PNB 2264 Fall 2008 Kimball Lecture...

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