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Materials can move across the cell’s membrane

Materials can move across the cell’s membrane. Chapter Two – Section Three. Quickie Review. All cells have a cell membrane surrounding them Cells need STARTER materials to do different processes (photosynthesis and cellular respiration)

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Materials can move across the cell’s membrane

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  1. Materials can move across the cell’s membrane Chapter Two – Section Three

  2. Quickie Review • All cells have a cell membrane surrounding them • Cells need STARTER materials to do different processes (photosynthesis and cellular respiration) • Cells need to get rid of Waste products and items that they make for the body

  3. Colored Water Demonstration • Describe what you saw…. • Animation: How Diffusion Works

  4. Some materials move by DIFFUSION • Diffusion is when molecules spread out from where there is a lot – to where there is not a lot. • It happens because molecules are in Constantmotion in all directions (everywhere) • Examples: • Any scent that “travels” through air • Food dye through water • Water, CO2, O traveling in and out of cells

  5. “Concentration” – page 57 • Diffusion is movement from areas of High “concentration” to areas of Low “concentration” until there is EQUILIBRIUM (balance) • The greater the difference in concentration, the faster the movement (diffusion) • Adding Salt to Ocean Water…slow diffusion • Adding Salt to Fresh Water…fast diffusion

  6. Diffusion in cells happens the same way • Small molecules (like O, H2O, CO2) can move through the cell membrane without problem • Diffusion across a Cell Membrane • This is called PASSIVE TRANSPORT – Movement with out Energy required

  7. Passive Transport in cells –No Energy needed • Most Passive Transport happens with smaller molecules (O, H2O, CO2) • Some Molecules are Large (C6H12O6) and require special “doors” to move through called “Passive Transport Proteins”

  8. H2O • H2O H20 H2O • H20 H2O • H2O H2OH2O • H2O H2O • H20 • BALANCE THIS PICTURE

  9. Second Type of Passive Transport • Osmosis • It is the “Diffusion” of Water ONLY across the cell membrane • It move on its “own” until there are the sameamount of H2O’s on each side (Equilibrium) • Example: Page 59 – Wilting plants

  10. Active Transport in cells • Opposite from Passive in that this molecule movement needsENERGY Movement from areas ofLow Concentration to areas ofHigh Concentration • This usually happens when the molecules are very LARGE in size, or when more molecules have to get out of the cell, or come in the cell • Example: Page 60 – Iguanas • Active Transport Animation

  11. Two types of Active Transport • Endocytosis • When molecules that are too big to go through the cell membrane, need to get IN the cell • Exocytosis • When molecules that are too big to go through the cell membrane, need to get OUT of the cell • Example: Plastic Bag demo • Amoeba eating

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  13. Cell Size will affect how molecules move • Almost all cells are small • Average human cell is .005mm in diameter • Lots of things need to go in and out of cell for jobs to be done. • Surface Area is needed • More surface – more exchange can take place

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