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Passive Transport

Passive Transport. Bio 5-1. Passive transport. The ability for selected substances to pass through the cell membrane without any help or added energy Diffusion Osmosis Facilitated Diffusion Ion channels. Diffusion. Molecules move from areas of high concentration to low concentration.

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Passive Transport

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  1. Passive Transport Bio 5-1

  2. Passive transport • The ability for selected substances to pass through the cell membrane without any help or added energy • Diffusion • Osmosis • Facilitated Diffusion • Ion channels

  3. Diffusion • Molecules move from areas of high concentration to low concentration

  4. Concentration gradient • Differences in concentration across a distance • *remember concentration is how much “stuff” there is in something*

  5. Why/how do the molecules move • Kinetic energy – all substances are constantly moving, the molecules are bumping into one another in moving off in new directions • Greater KE = faster molecular movement

  6. Equilibrium • The substance is the same throughout • All substances want to reach equilibrium

  7. What gets diffused • Only molecules that are soluble in lipids • Carbon dioxide, oxygen and so on • AND very small molecules that do not dissolve in lipids because they fit between the pores

  8. Osmosis • Process by which water moves from higher to lower concentration gradients

  9. hypOtonic means the cell swells O Direction of osmosis

  10. How cells regulate water • Contractile vacuole – absorbs water and then squeezes it out, outside the cell (requires energy) • Pump out solutes – lowers concentration inside cell so water does not want to come in

  11. Plant Cell a. ________________ b. __________________ c. _________________ • Plant cell wall – rigid non expanding structure that limits the amount of water that can be in cell • Turgor pressure – force of expanding cell pushing on cell wall • Plasmolysis – when cell membrane shrinks away from cell wall due to lack of water (hypertonic) results in plant wilting hypotonic hypertonic isotonic

  12. hypotonic hypertonic • Some cells can not regulate concentrations • Red blood cells isotonic If it bursts… cytolysis

  13. Facilitated Diffusion • Used for molecules that cannot readily diffuse through the membrane • Uses carrier proteins in membrane (integral proteins) • Moves molecules from high concentration to low

  14. Glucose is one major molecule that uses this. It can work in either direction *** proteins are specific to the molecule they carry, they will not allow any others

  15. Ion channels • These transport specific ions • Na+Cl- K+Ca+ and more • Some channels are always open, some are gated • Gates open to one of 3 stimuli • Stretching the plasma membrane • Electrical signal • Chemical signal

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