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Regents Biology 2006-2007 Cell Membranes & Movement Across Them.

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Presentation on theme: "Regents Biology 2006-2007 Cell Membranes & Movement Across Them."— Presentation transcript:

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2 Regents Biology 2006-2007 Cell Membranes & Movement Across Them

3 Regents Biology Cell (plasma) membrane Cells need an inside & an outside… separate cell from its environment cell membrane is the boundary IN food - sugars - proteins - fats salts O2O2 H2OH2O OUT waste - ammonia - salts - CO 2 - H 2 O products - proteins cell needs materials in & products or waste out

4 Regents Biology Lipids of cell membrane Membrane is made of special kind of lipid phospholipids split personality Membrane is a double layer phospholipid bilayer inside cell outside cell lipid repelled by water attracted to water phosphate

5 Regents Biology Semi-permeable membrane Cell membrane controls what gets in or out Need to allow some materials but not all to pass through the membrane semi-permeable only some material can get in or out aa H2OH2O sugar lipidssalt waste So what needs to get across the membrane? O2O2

6 Regents Biology Cell membrane channels Need to make doors through membrane protein channels allow substances in & out specific channels allow specific material in & out H 2 O channel, salt channel, sugar channel, etc. inside cell outside cell sugaraa H2OH2O salt waste

7 Regents Biology Protein channels Proteins act as doors in the membrane channels to move specific molecules through cell membrane HIGH LOW

8 Regents Biology Molecules move from high to low Diffusion move from HIGH to LOW concentration

9 Regents Biology Diffusion Move from HIGH to LOW concentration passive transport no energy needed diffusionosmosis diffusion of water

10 Regents Biology Diffusion Move from HIGH to LOW concentration directly through membrane simple diffusion no energy needed help through a protein channel facilitated diffusion (with help) no energy needed HIGH LOW

11 Regents Biology Simple vs. facilitated diffusion inside cell outside cell lipid inside cell outside cell H2OH2O simple diffusionfacilitated diffusion H2OH2O protein channel

12 Regents Biology Active transport Cells may need molecules to move against concentration hill need to pump uphill from LOW to HIGH using energy protein pump requires energy ATP

13 Regents Biology Transport summary simple diffusion facilitated diffusion active transport ATP

14 Regents Biology 2006-2007 Osmosis Movement of Water Across Cell Membrane

15 Regents Biology Osmosis Water is very important, so we talk about water separately Osmosis diffusion of water from HIGH concentration of water to LOW concentration of water across a semi-permeable membrane

16 Regents Biology Keeping right amount of water in cell Hypotonic condition a cell in distilled water high concentration of water around cell cell gains water problem: cells gain water, swell & can burst Plant cells- become turgid, which which is normal Animal cells-burst and die freshwater No problem, here KABOOM! 1

17 Regents Biology Keeping right amount of water in cell Isotonic condition no difference in concentration of water between cell & environment Water flows equally into and out of cell cell in equilibrium Plant cells: Flaccid Animal cells: Normal balanced I could be better… Thats better! 2

18 Regents Biology Keeping right amount of water in cell Hypertonic solution a cell in salt water low concentration of water around cell cell loses water Plant cells- shrink, can survive for a time Animal cells- shrink and die saltwater I will survive! Im shrinking, Im shrinking! 3

19 Regents Biology Ice Fishing in Barrow


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