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CELL MEMBRANE

Learn about the cell membrane's functions, structure, and proteins. Discover how this lipid bilayer selectively controls what passes in and out of the cell, its fluid mosaic model, and the role of integral and peripheral proteins. Explore the importance of the lipid bilayer and cholesterol molecules in cell membrane stability.

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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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