cell transport mechanisms student fall 2011

cell transport mechanisms student fall 2011 - The plasma...

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The plasma membrane functions § The functions of the plasma membrane include: § Isolation § Regulation of exchange with the environment § Sensitivity to the environment § Structural support
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Plasma Membrane § Physical barrier - separates intracellular fluids from extracellular fluids § Helps in maintaining homeostasis § Plays a dynamic role in cellular activity selectively permeable
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Fluid Mosaic Model § Double bilayer of phospholipids § Phospholipids have hydrophobic tails and hydrophilic heads CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH3 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH CH CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH3 CH2 CH2 CH3 C H 3 CH3 N + O O O P O C H 2 C H C H 2 C O C O O O Phosphate group Hydrophilic head Hydrophobic tails
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The plasma membrane includes proteins § Integral proteins § Within the membrane § Peripheral proteins § Bound to inner or outer surface of the membrane
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The plasma membrane includes proteins § Anchoring proteins (stabilizers) § Attach to inside or outside structures § Recognition proteins (identifiers) § Label cells as normal or abnormal § Enzymes § Catalyze reactions § Receptor proteins § Bind and respond to ligands (ions, hormones) § Carrier proteins § Transport specific solutes through membrane § Channels § Regulate water flow and solutes through membrane
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Structures on the plasma membrane surfaces Apical surface Lateral surface Microvilli, Cilia, Stereocilia Specialized junctions
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Features of Apical Surface of Epithelium - Microvilli § Projections that increase surface area § Folding of the plasma membrane http://cellbio.utmb.edu/microanatomy/epithelia/epith_lec.htm
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Features of Apical Surface of Epithelium - Cilia § These structures are designed for motility . § Epithelia that need to move substances across their surface (like mucous in the air passages) have cilia. § Each cilium or flagellum has a basal body located at its base. § Basal bodies anchor the cilia or flagella and are thought to be responsible for their formation. § They look like centrioles and are believed to be derived from them
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§ Flagella : (ex) spermatoza § Extra long cilia § Moves cell http://www.lbl.gov/Science-Articles/Archive/sabl/2006/Jul/02.html
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Cell junctions – 3 groups § Tight junction § designed to restrict the movement of material between the cells they link § Gap junction § create cytoplasmatic communication bridges between cells § Anchoring junction § attach cells to one another or to extracellular matrix
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http://www.phschool.com/science/biology_place/biocoach/biomembrane2/junctions.html Membrane Junctions Tight junction Anchoring junction Gap junction
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Tight Junctions § An intercellular junction between cells in which the outer layers of the cell membranes fuse, § reducing the ability of larger molecules and water to pass between the cells
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This note was uploaded on 01/07/2012 for the course BIO 2401 taught by Professor Joselchou during the Spring '11 term at Collins.

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cell transport mechanisms student fall 2011 - The plasma...

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