Cell Membrane and Transport.pptx

Proteins in the bilayer 2 types of proteins based on

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Proteins in the bilayer 2 types of proteins (based on their position on/in the membrane) Intrinsic proteins / integral proteins Extrinsic proteins / peripheral proteins Intrinsic proteins Penetrate the hydrophobic interior; can stick out of the surface of both intracellular/extracellular region Span the membrane – trans membrane proteins Extrinsic proteins Stick to the inner or outer surface of the membrane
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3. Proteins Transport proteins Passage for ions & polar molecules Specific 2 types channel & carrier proteins Facilitated and active transport Enzymes Eg. Enzymes in cells lining the small intestines Receptor o Recognises molecules on the extracellular environment. Eg. Hormones and neurotransmitter o When molecules bind to signaling receptors, It triggers chemical reaction In the cell Eg. Insulin - change glucose into glycogen
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4. Glycolipids & glycoproteins Cell-cell Recognition Act as cell markers/antigens Each cell has its own distinct carbohydrate chains Cells can recognise each other
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Through the cell membrane… Simple diffusion Facilitated diffusion Osmosis Active Transport Bulk transport 5 mechanisms of exchange between cell and its environment
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Passive Transport - no ATP is required 1. diffusion : - movement of molecules of a solute from areas of high to low concentration (down a concentration gradient) until equilibrium is reached - Through partially permeable membrane (phospholipid bilayer in cells) - equilibrium : steady state where equal numbers of molecules move in each direction - concentration gradient : differences in concentration of a substance across a space
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*Diffusion Diffusion movement from [higher] [lower] concentration
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Simple diffusion Passive transport no ATP used Net movement of small, uncharged molecules From region of high low concentration Down the concentration gradient until it reaches equilibrium Through partially permeable membrane (phospholipid bilayer in cells) Random movements of molecules Natural kinetic energy in molecules/ions
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* Diffusion will also happen across a cell membrane as long as there is a difference in concentration and the membrane will let the molecule pass through until equilibrium and then moves randomly
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Solutes move across the membrane until equilibrium is reached
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Factors affecting the rate of diffusion across a membrane Steepness of the concentration gradient Temperature Surface area Nature of molecules/ions
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Diffusion
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Steepness of the concentration gradient Greater the difference in concentration, faster the net rate of diffusion
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