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Schedule Why was it so darn cold? Go over quizzes Current event Membranes Membranes worksheet (finish for HW as needed) Tomorrow: Review membranes, Osmosis/Diffusion Membranes Quiz next Monday Mini-unit test next Wednesday
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DNA Draw how a water molecule surrounds a cation like Na+
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Water Soluble
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Membrane Structure and Function
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Hydrophobic Vs. Hydrophilic Water-fearing Fats, oils, rubbers Non-polar Water-loving Polar, ionic Has some charge
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Amphipathic Molecules Have both hydrophilic and hydrophobic regions Phospholipids have hydrophilic heads and hydrophobic tails
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Soaps/Detergents
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Phospholipids
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Phospholipid Bilayer Phospholipids naturally arrange themselves to keep hydrophobic portions away from water
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Membranes Both wrap the entire cell and individual organelles Very movable – like play-dough
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Fluid Mosaic Model Proteins are embedded in the membrane These proteins have many different functions
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Membrane Protein Functions Transport Enzymatic Activity Binding of messengers Intercellular connections Cell recognition Attachment
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Membrane Carbohydrates Important in cell-cell recognition Short polysaccharides Often bonded to proteins (glycoproteins) Distinguish cells – i.e. blood types
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What Makes Each Membrane Different? The proteins and carbohydrates present E.g. thylakoid membranes have chlorophyll proteins, red blood cells have A/B markers etc.
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Special Membranes = Special Organelles Controls what gets into the organelle. So mitochondria has only the materials necessary for respiration – nothing else to get in the way!
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Selective Permeability Membrane is selective in what molecules can pass through and how quickly they pass Energy must sometimes be used to transport molecules
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Simple Permeability Small non-polar molecules rapidly pass through membrane Very small polar molecules can slip through Larger polar molecules cannot Very impermeable to ions
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Cell Wall v. Plasma Membrane Rigid Carbohydrates Controls structure Not in animal cells Flexible Phospholipids Controls entry In all cells
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