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Cell Transport. Moving Materials Into and Out of the Cell. Transport through the cell membrane. Extracellular fluid ~ The fluid that surrounds cells. (Interstitial fluid) Intracellular fluid ~ The fluid inside of a cell. ( Cytosol ). Plasma Membrane.
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Cell Transport Moving Materials Into and Out of the Cell
Transport through the cell membrane • Extracellular fluid ~ The fluid that surrounds cells. (Interstitial fluid) • Intracellular fluid ~ The fluid inside of a cell. (Cytosol)
Plasma Membrane • Regulates what enters and leaves the cell and also provides protection and support. • Phospholipidbilayer
Plasma Membrane • Semi-permeable or selectively permeable • Proteins – channels and pumps that help to move material across the cell membrane. • Carbohydrates – act like chemical identification cards
Solution • Solvent – substance that contains substances; responsible for doing the dissolving • Solute – substance dissolved in the solvent • Ex: salt water • Salt = solute water = solvent
Concentration • Cytoplasm contains a solution of may different substances in water • Amount of substances vs amount of water • Concentration gradient – drives diffusion and osmosis
Hypotonic, Hypertonic, Isotonic • Hypotonic – lower concentration of solutes • Hypertonic – higher concentration of solutes • Isotonic – concentration is the same
Extracellular Fluid Intracellular Fluid
Extracellular Fluid Intracellular Fluid
Isotonic solution ~ The concentration of dissolved salts in the intracelluar fluid is the same as it is in the extracellular fluid. Note that normal red blood cells look a bit like Cheerios. They are round and flat with a dent in the middle.
Hypertonic solution ~ The concentration of dissolved materials is greater in the extracellular fluid than it is in the intracellular fluid. Plasmolysis ~ Cell shriveling due to a decrease in internal pressure.
Hypotonic solution ~ The concentration of dissolved materials in the intracellular fluids is greater than that in the extracellular fluid. Cytolysis ~ Cell bursting due to internal pressure.
Dynamic equilibrium • The point at which concentrations of a molecule or compound is equal both inside and outside.
Passive Transport • Passive transport is the movement of materials through the cell membrane that does not require the use of energy. • Diffusion ~ The movement of particles from an area of high concentration to low concentration • Osmosis ~ The diffusion of water through a semi-permeable membrane. In the case of cells, this will be the cell membrane.
Passive Diffusion • Movement of substances is through the cell membrane from a high concentration to low concentration • Osmosis is a type of passive diffusion where water molecules across the cell membrane
Facilitated Diffusion • Substances cross the cell membrane through protein channels (specifically designed for that substance) • No energy is used
Active Transport • Movement of substances into and out of the cell using energy • Protein pumps are necessary; changes in protein shapes is vital for this to occur
Active Transport • Requires the use of cell energy (ATP) • Endocytosis: process of taking material into the cell by folding of the cell membrane. • Phagocytosis: “cell eating” • Pinocytosis: cell takes in liquid from outside the cell
Active Transport • Exocytosis: release of materials from the cell • Membrane of the vacuole surrounding the material fuses with the cell membrane, forcing the contents out of the cell
Videos!! • Plasma Membrane: • http://www.youtube.com/watch?v=owEgqrq51zY&feature=related • Facilitated diffusion: • http://www.youtube.com/watch?v=s0p1ztrbXPY&NR=1 • Active Transport: • http://www.youtube.com/watch?v=STzOiRqzzL4