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Chapter 6.3: Membranes regulate the traffic of molecules College Prep Biology Mr. Martino.

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Presentation on theme: "Chapter 6.3: Membranes regulate the traffic of molecules College Prep Biology Mr. Martino."— Presentation transcript:

1 Chapter 6.3: Membranes regulate the traffic of molecules College Prep Biology Mr. Martino

2 6.3 Cell Membranes Cell membranes make the E in chemical bonds available for metabolic reactions Kinds and amounts of substances different on either side of membrane – membrane is selectively permeable CO 2, O 2, water, and small nonpolar molecules move easily across Large, polar molecules and ions do not move freely across These require various proteins

3 Concentration Gradients Brownian Motion – continuous random movement of particles due to temp. differences Concentration gradient: the difference in conc. of particles on one side of a membrane as opposed to the other

4 Diffusion Diffusion: the tendency for particles to move from areas of high concentration to areas of low conc. Molecules naturally move “with” conc. Gradient Diffusion is fastest when gradient is steep

5 Active transport: requires E to move substances across a membrane Transport protein pumps the substance against the conc. gradient Usually use ATP

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7 Movement of Water Osmosis: the diffusion (passive transport) of water Hypertonic Solution: has a higher conc. of solutes than the cell Water will leave cells and cells will shrivel Hypotonic Solution: had a lower conc. of solutes than the cell Water will rush into cells and cells will swell

8 Turgor (hydrostatic) pressure: the internal force pushing outward in plant cells Cell wall prevents the uptake of too much water Isotonic Solution: the conc. of particles inside the cell is = to the conc. of the particles outside the cell Movement continues – just no net movement

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10 Endocytosis and Exocytosis Exocytosis: process of how cells export bulky materials from the cytoplasm Ex. Tear and insulin formation Endocytosis: process of how cells import macromolecules Phagocytosis: cellular eating Pinocytosis: cellular drinking Receptor-mediated endocytosis: highly specific due to receptor proteins

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