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Cells.pdf - Cells I. Cell Structure and Function A. Cell...

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CellsI. Cell Structure and FunctionA. Cell Theory1. A cell is the basic structural and functionalunit of living organisms2. All cells come from pre-existing cells3. The activity of an organism depends onboth the individual and the collectiveactivities of its cells
CellsA) Principle of Complementaritythebiochemical activities of cells are dictatedby their specific subcellular structures4. Most cells are capable of self-reproductionB. Typical cells are made of three main parts:1. Cell (plasma) membrane2. Nucleus3. Cytoplasm and cytoplasmic organelles
CellsC. Cell Membrane1. A flexible,selectively permeablemembranethat defines the extent of a cell by separatingintracellular fluid (ICF) from the extracellularfluid (ECF)2. The Fluid Mosaic Model1972A) Composed of a phospholipidbilayer1) Hydrophilic heads face outward2) Hydrophobic tails face inward
Cellsa) Creates ahydrophobic corethat givesthe membrane selective permeability3) Two layers are moveable (fluid)B) The plasma membrane contains manyembedded structures1) Proteins:
Cellsa)Transmembraneproteinsproteins thattypically extend all the wayacross themembrane and play a role in many functionsi)Transportproteins(a)Channels, pores,carriers, andpumpsii)Enzymesiii)Receptorsiv)Intercellularjunctionsv)Cell-cell recognition
Cellsb) Surface (peripheral) proteinsproteins thatare attached to either side of the membraneand are mostly involved with:i) Acting asenzymes & receptorsii) Attaching to the cytoskeleton formovement and supportiii) Aid in changing the shape of the cell
Cells2) Cholesterol & Steroidslipid structuresthat help to stabilize the membranea)Necessarydue to the lack of a cell wall3. Associated StructuresA) Microvilli (“little shaggy hairs”)finger-likeprojections that increase the surface area ofthe plasma membraneB) Membrane junctions
Cells1) Tight junctionsmembrane proteins fuse thetwo adjacent cell membranes togethera)Prevent the movement of substancesbetweencells2) Desmosomesanchoring junctions that areassociated with protein filamentsa)Providestrength3) Gap junctionsmembrane proteins formchannels between adjacent cellsa)Allowimpulse transmission between cells

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Term
Summer
Professor
P.Deleon
Tags
Cell Cycle, Mitosis, ECF, c Cell Membrane

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