all bio - Robert Hooke is credited with introducing the...

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Robert Hooke is credited with introducing the word ‘cell’ into biology The cell theory o The cell in the structural unit of life o All organisms are composed of 1 or more cell types o Cells can arise only by the division of a pre-existing cell Basic cell properties o Highly complex and organized o Activity controlled by a genetic program o Can reproduce o Assimilate and utilize energy o Carry out chemical reactions – enzymes o Engage in mechanical activities o Respond to stimuli o Capable of self-regulation o Evolve Two classes of cells on earth o Prokaryotic Bacteria Structurally simpler o Eukaryotic Protists, fungi, plants, animals Structurally more complex The DNA is packaged differently in a prokaryotic cell than a eukaryotic Eukaryotic cells have compartments which are membrane bound structures dedicated to a particular function and components which are not bound by membranes The usual size range for a cell is 10^-6 m An organelle is a membrane bound compartment with a characteristic content and a specific function A compartment is a separate section where something can be considered in isolation from other things o Compartmentalizes divide a whole into separate parts or sections o Sequesters keep contents from mixing with others
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biological membranes contain a hydrated lipid bilayer amphipathic is having both hydrophobic (non-polar) and hydrophilic (polar) regions membrane fluidity is determined by o nature of lipids in membrane unsaturated lipids increase fluidity saturated lipids reduce fluidity o temperature warming increases fluidity = liquid crystal cooling decreases fluidity = crystalline gel balance between ordered (rigid) structure and disordered structure allows: o mechanical support and flexibility o dynamic interactions between membrane components proteins can come together reversibly o membrane assembly and modification cholesterol regulates membrane fluidity fluid = individual lipid molecules move mosaic = diverse particles penetrate the lipid layer fluid-mosaic model o bilayer of amphipathic lipids o proteins integral span the lipid bilayer peripheral membrane proteins associate with the surfaces of the lipid bilayer lipid-anchored proteins attach to a lipid in the bilayer o components are mobile o components can interact
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in plasma membranes, the outer leaflet contains glycolipids and glycoproteins all membranes share common properties o 6nm thick o stable o flexible o capable of self assembly lipids move easily and laterally within leaflet lipid movement to other leaflet is slow membrane proteins diffuse within the bilayer o movement of proteins is restricted o some proteins do not move o rapid movement is spatially limited o long range diffusion is slow o biochemical modification can dramatically alter protein mobility in the membrane
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