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Published byLauren Morris Modified over 9 years ago
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Class Notes 4:Cellular Transport and the Plasma Membrane
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I. Structure of the Plasma Membrane A. All cells have a plasma membrane. It is a PHOSPHOLIPID BILAYER B. A phospholipid is a molecule with 3 parts: 1. Polar phosphate 2. Glycerol 3. Non- polar fatty acid tail
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II. Other molecules of the cell membrane A. Cholesterol -strengthens the membrane. B. Transport proteins-like tunnels allowing certain substances in and out. C. Carbohydrates- allow cells to identify eachother.
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III. Methods of cellular transport: A. The membrane has SELECTIVE PERMEABILITY- some but not all materials can cross. B. Materials can move in and out of the cell in the following ways: 1. Passive Transport = no energy required a. Diffusion b. Facilitated diffusion 2. Active Transport= energy required 3. Endocytosis 4. Exocytosis
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IV. Passive transport A. Very small molecules like 0 2 can pass right through the plasma membrane by diffusion. B. Facilitated diffusion allows larger particles to go through transport proteins.
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V. Active Transport A. Movement of materials through a membrane against a concentration gradient is called Active Transport and requires energy.
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B. Endocytosis Some cells can take in large molecules, groups of molecules, or even whole cells = ENDOCYTOSIS
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C. Exocytosis 1. Exocytosis is the explosion or secretion of materials from the cell (wastes, hormones) 2. Endocytosis and Exocytosis require energy!
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Summary Describe the structure of the plasma membrane. How do molecules get in and out? What is the difference between active and passive transport?
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