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Membrane TransportMembrane Transport
Pages 78-85 include information on
membrane transport
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Cell Membrane aka Plasma MembraneCell Membrane aka Plasma MembraneCell Membrane aka Plasma MembraneCell Membrane aka Plasma Membrane
Outsideof cell
Insideof cell(cytoplasm)
Cellmembrane
Proteins
Proteinchannel Lipid bilayer
Carbohydratechains
• Composed of double layer of phospholipids and proteins (A phospholipid bilayerphospholipid bilayer)
• Surrounds outside of ALL cells• Is semipermeablesemipermeable• Watch This
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PhospholipidsPhospholipidsPhospholipidsPhospholipids
• Heads contain glycerol & phosphate and are hydrophilic (attract water)
• Tails are made of fatty acids and are hydrophobic (repel water)
• Make up a bilayer where tails point inward toward each other
• Can move laterally to allow small molecules (O2, CO2, & H2O to enter)
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The Cell Membrane is The Cell Membrane is FluidFluid
The Cell Membrane is The Cell Membrane is FluidFluid
FLUID MOSAIC MODEL: Molecules in cell membranes are constantly moving and changing
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Cell Membrane ProteinsCell Membrane ProteinsCell Membrane ProteinsCell Membrane Proteins
• Proteins help move large molecules or aid in cell recognition
• Peripheral proteins are attached on the surface (inner or outer)
• Integral proteins are embedded completely through the membrane
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Recognize “self”
GLYCOPROTEINSGLYCOPROTEINS
Glycoproteins have carbohydrate tails to act as markers for cell recognition
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•Lies immediately against the cell wall in plant cells
•Pushes out against the cell wall to maintain cell shape
Cell Membrane in PlantsCell Membrane in PlantsCell Membrane in PlantsCell Membrane in PlantsCell membrane
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Remember The Heterotroph Hypothesis?
Remember The Heterotroph Hypothesis?
Cell Membrane Forming Spontaneously?!
Two Forms Of Membrane Transport
Two Forms Of Membrane Transport
Concepts:
Equilibrium
Concentration gradients
Polarity
Molecule size
Electrical Charge
Passive vs. Active
Passive TransportPassive Transport
Passive transport requires no energy!
Diffusion - Movement from [hi] to [low]
Osmosis - Diffusion of water
Facilitated Diffusion - with carrier proteins
Active TransportActive Transport
Active transport requires energy
Ion Channels Ion Pumps Endocytosis
PhagocytosisPinocytosis
Exocytosis