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The Cell in Its Environment

The Cell in Its Environment. Francisci. The Cell Membrane. Cell membrane separates the cell from outside world Selectively permeable – Only allows certain substances to pass through the membrane while others can not (based on size). What is allowed in and out?.

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The Cell in Its Environment

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  1. The Cell in Its Environment Francisci

  2. The Cell Membrane • Cell membrane separates the cell from outside world • Selectively permeable – Only allows certain substances to pass through the membrane while others can not (based on size)

  3. What is allowed in and out? • Cells must let in oxygen and food • Waste products must leave the cell • Substance can move into and out of the cell by active or passive transport

  4. Passive Transport • Movement of particles across the cell membrane WITHOUT the use of cellular energy • Molecules move around randomly • Molecules spread out from an area of high concentration to an area of low concentration

  5. Types of Passive Transport: • Diffusion – Random movement of molecules from an area of high concentration (a lot in one spot) to an area of low concentration (not as much in one spot) • NO USE OF CELLULAR ENERGY

  6. Examples of Diffusion: • Perfume: perfume gas molecules diffuse into the air when put on so you can smell it • Oxygen: Moves from high concentration outside of the cell to lower concentration inside the cell • Diffusion continues until molecules are spread out equally (equilibrium)

  7. Types of Passive Transport: • Osmosis – Diffusion of water molecules through a selectively permeable membrane • NO USE OF CELLULAR ENERGY • Cells cannot function without water • Water moves from high to low concentrations

  8. Active Transport • Active Transport: The movement of materials through a cell membrane USING cellular energy • Materials too large so cellular energy is needed to move materials along • Moves materials from an area of low concentration to an area of high concentration such as ions, glucose and amino acids

  9. Types of Active Transport • Endocytosis: Allows large materials to enter the cell by being enclosed by part of the cell membrane • Cell membrane in-folds around food particle • “Cell Eating” • Forms food vacuole and digests food • Ex. White blood cells eating bacteria

  10. Types of Active Transport: • Exocytosis: Forces large materials out of the cell • Membrane surrounding the material fuses with cell membrane • Cell changes shape – requires energy • Ex. Hormones or wastes released from the cell

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