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Published byHester Marsh Modified over 8 years ago
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Cell Processes Transport
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I. Transport Cell Membrane helps maintain homeostasis by regulating what substances enter and leave the cell
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1. Passive Transport - movement of materials across a membrane which requires no cellular energy -Due to a difference in concentration- molecules move down concentration gradient
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a. Diffusion - movement of materials from an area of high concentration to area of low concentration -may or may not include a membrane -only small, non-polar molecules diffuse through membrane
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Driven by: kinetic energy Diffusion naturally leads to: equilibrium Equilibrium: when all the movement of molecules is equal
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B. Osmosis -passive transport of water across a membrane from high concentration to low concentration 1.Hypertonic: Plasmolysis- shrinking of a cell from loss of water
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2. Hypotonic: Cytolysis- swelling and bursting of a cell caused by internal pressure Turgor Pressure- pressure that builds up in a cell due to the inward flow of water
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3. Isotonic:
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C. Channel Proteins -Used when molecules have a charge (they would get stuck in middle) D. Facilitated Diffusion -Used when substances are too large to pass through -Diffusion through carrier proteins
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Contrast Channel Protein vs. Facilitated Diffusion
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2. Active Transport -Requires cellular energy ( ATP) -Sometimes the cell must move materials against their concentration gradient
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a. Cell Membrane Pump -Uses carrier proteins to transport substances against the concentration gradient
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B. Endocytosis -Ingestion of: fluid or macromoleucules -Two Types: Pinocytosis: cell drinking Phagocytosis: cell eating -Forms a vesicle from cell membrane Ex: White blood cell
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c. Exocytosis -Vesicles in cytoplasm fuse with the membrane and release contents outside cell
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