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Membranes

Membranes. Cell membrane = Plasmalemma = Plasma membrane Surrounds cells and most organelles Forms a network of passages. Mitochondria, chloroplasts, and the nucleus all have a double membrane. Functions of plasmalemma. Keep cell contents together and separate from other cells

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Membranes

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  1. Membranes Cell membrane = Plasmalemma = Plasma membrane Surrounds cells and most organelles Forms a network of passages

  2. Mitochondria, chloroplasts, and the nucleus all have a double membrane

  3. Functions of plasmalemma • Keep cell contents together and separate from other cells • Controls movement of substances into and out of cells • Allow communication between cells • Attachment for intracellular cytoskeleton, cell walls and intercellular adhesions

  4. Membranes are made of Phospholipids Hydrophilic Polar head Hydrophobic Non-polar tails

  5. Hydrophobic tails Hydrophilic heads Watery cytosol

  6. Water outside cell Hydrophobic tails Watery Cytoplasm

  7. Fluid mosaic theory • Phospholipids are not bound to each other • Like oil on water • Water inside and outside the cell http://www.youtube.com/watch?v=ULR79TiUj80&feature=related (fluid mosaic model, 1.5 min)

  8. Permeability • Membranes are selectively permeable • Allow some molecules through but not all

  9. Permeability of membrane • Some membranes impermeable (eg surfaces designed to retain water such as skin, scales, exoskeletons)

  10. MENU Quick Quiz Key Words Videos Extra slides Exercises

  11. Key words Back to menu • Phospholipids • Bilayer • Fatty tails • Phosphate head • Impermeable • Permeable • Large molecules • Ions • Fluid Mosaic

  12. (VERY) Quick quiz Back to menu • ____ are the main component of membranes • They consist of hydrophobic ____ • And a hydrophilic ____ • They also have integral and peripheral ____ Answers

  13. (VERY) Quick quiz Back to menu • Phospholipids are the main component of membranes • They consist of hydrophobic tails • And a hydrophilic head • They also have integral and peripheral proteins

  14. Exercise Back to menu • Workbook pp50-52, qq18-20 and 22-23 • Booklet p3 • READING • Pathfinder p48 (or p42) Enzymes & reaction rate • Excellence in Biology pp114-6

  15. Videos Back to menu • http://www.youtube.com/watch?v=E90D4BmaVJM&feature=related (10 min, includes biotechnology) • http://www.teachersdomain.org/asset/tdc02_int_membraneweb/ (interactive - membrane)

  16. Glycoproteins & glycolipids for cell recognition http://www.5min.com/Video/Proteins-as-the-Mosaic-of-the-Cell-Membrane-150624158 Back to menu

  17. Peripheral proteins Back to menu Partially embedded • intrinsic – inside cell • extrinsic – outside cell

  18. OIL AND WATER Back to menu I told you this would be important!

  19. Trans-membrane (integral) proteins Back to menu • involved in facilitated and active transport

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