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CELL MEMBRANE

CELL MEMBRANE. I. Functions: Selectively Permeable - controls which substances pass into and out of cell. Site of important metabolic reactions. Outpouchings & infoldings increase surface area. CELL MEMBRANE. II. Structure: Composed mainly of lipids & proteins. Fluid Mosaic Model –

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CELL MEMBRANE

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  1. CELL MEMBRANE I. Functions: • Selectively Permeable - controls which substances pass into and out of cell. • Site of important metabolic reactions. • Outpouchings & infoldings increase surface area.

  2. CELL MEMBRANE II. Structure: • Composed mainly of lipids & proteins. • Fluid Mosaic Model – 1. behaves more like a fluid than a solid. 2. lipids & proteins can move so their pattern (mosaic) changes.

  3. Bilayer of Phospholipids

  4. CELL MEMBRANE • Bilayer of phospholipids 1. Heads a. Hydrophilic - "water loving" b. Attracted to H2O c. Orient toward surfaces close to H2O

  5. Structure of Lipid Bilayer

  6. CELL MEMBRANE 2. Tails a. Hydrophobic - "water fearing" b. Repelled by H2O c. Orient away from surface toward inner portion of membrane d. Lipid soluble/ water insoluble

  7. Watery Environments

  8. CELL MEMBRANE 3. Both sides of cell membrane are surrounded by water. This causes the phospholipids to form two layers: a. Hydrophilic heads point outward. b. Hydrophobic tails point inward

  9. CELL MEMBRANE • This lipid bilayer structure is important in the membrane's function of being selectively permeable. • (only allows fat-soluble substances through)

  10. Proteins in Plasma Membrane Peripheral Integral Globular Fibrous

  11. CELL MEMBRANE • Proteins 1. Peripheral proteins a. located on surface (interior or exterior) b. Help cell to change shape (phagocytosis)

  12. CELL MEMBRANE 2. Integral proteins • embedded in the lipid bilayer. • some have carbohydrates attached which may be receptor sites for chemicals or viruses. • some form channels, pores, or 'shuttles' that allow substances to pass through.

  13. CELL MEMBRANE a. Fibrous: • tightly coiled & rodlike • may span from cell's inside to outside • communicate between opposite ends • specialized receptors to hormones

  14. CELL MEMBRANE b. Globular: • compact • span the membrane • form channels specific for certain ions & molecules • form pores that allow water through

  15. CELL MEMBRANE • (Proteins help to make cell membrane selectively permeable. They allow non-fat solubles to pass through)

  16. CELL MEMBRANE • Cholesterol Molecules 1. embedded in interior of membrane 2. give stability to membrane

  17. Label the Plasma Membrane

  18. Plasma Membrane Animation • http://www.wiley.com/legacy/college/boyer/0470003790/animations/membrane_transport/membrane_transport.htm

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