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Cell Transport

Cell Transport. EQ: Explain how active and passive transport help the cell maintain homeostasis. SC B-2.5 Explain how active, passive, and facilitated transport serve to maintain homeostasis of the cell. CELL TRANSPORT CHAPTER 7 SECTION 3. DEFINITIONS:

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Cell Transport

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  1. Cell Transport EQ: Explain how active and passive transport help the cell maintain homeostasis. SC B-2.5 Explain how active, passive, and facilitated transport serve to maintain homeostasis of the cell

  2. CELL TRANSPORTCHAPTER 7 SECTION 3 • DEFINITIONS: • Equilibrium: state that exists when the concentration of a substance is the same throughout a space • Concentration Gradient: difference in the concentration of a substance across a distance

  3. Passive Transport • dfn: movement of substances across a cell membrane without requiring energy expenditure by the cell • Types: • Diffusion • Facilitated Diffusion • Osmosis

  4. Passive transport • Particles are said to move “down their concentration gradient” • It is free!

  5. DIFFUSION • The movement of particles from regions of higher density to regions of lower density • Also called simple diffusion • Small, nonpolar molecules pass through the cell membrane by simple diffusion • Ex: oxygen, carbon dioxide

  6. SIMPLE DIFFUSION

  7. DIFFUSION RATE • Rate of diffusion affected by: • Temperature • Surface area • Concentration gradient • Size of molecule

  8. SIMPLE DIFFUSION ACROSS a MEMBRANE

  9. FACILITATED DIFFUSION • Same as simple diffusion (particles move down their concentration gradient) except particles require the use of a transport protein to cross cell membrane

  10. FACILITATED DIFFUSION • Because it requires a transport protein there is an upper limit to the # of molecules that can enter/exit a cell at any given moment • (called Tmax)

  11. Facilitated Diffusion • Glucose enters cells via facilitated diffusion

  12. OSMOSIS Osmosis : the diffusion of water from a more dilute solution  a more concentrated solution through a membrane that is permeable to water but not to the solute solute: what is dissolved in solvent solvent: what dissolves the solute

  13. Osmosis • Allows cells to maintain water balance as their environment changes http://www.stolaf.edu/people/giannini/flashanimat/transport/osmosis.swf

  14. Osmosis • Water Channels (called aquapores) in membrane to allow polar water molecules to enter/exit cell • In humans used by: • Respiratory system • Reproductive system • Urinary system (water conservation) • Digestive system • Homeostasis of body temperature

  15. Osmosis in Red Blood Cells • Hypertonic Solutions • Concentration of solutes higher than that in cytoplasm • Water follows its concentration gradient and moves from ______________ to ___________ • Cells will _________________, called crenation http://www.tvdsb.on.ca/WESTMIN/science/sbi3a1/cells/Osmosis.htm

  16. Osmosis in Red Blood Cells • If the solution is hypotonic, there is a lower solute concentration outside the cell than inside the cell • Water will move _____________ • The cell will __________, called hemolysis.

  17. Osmosis with Red Blood Cells • If the solution the red blood cell is in has the same concentration of water as the cytoplasm in the cell there will be _________ movement of water. • This is called an isotonic solution.

  18. Osmosis in Plant Cells

  19. PASSIVE TRANSPORT • http://www.northland.cc.mn.us/biology/Biology1111/animations/transport1.html

  20. ACTIVE TRANSPORT • Dfn: the movement of substances against their concentration gradient (against the flow) • Substances are moving from an area of lower concentration to an area of higher concentration • This requires the cell to use energy (ATP)

  21. ACTIVE TRANSPORT • TWO TYPES: • PUMPS • VESICLES • ENDOCYTOSIS • EXOCYTOSIS

  22. ACTIVE TRANSPORT PUMPS • Use a carrier protein (like facilitated diffusion) but requires expenditure of energy • Most common pump: • Na+/K+/ATP pump

  23. Na+/K+/ATP pump • A carrier protein that uses ATP (1) to actively transport sodium ions (3) out of the cell and potassium ions (2) into the cell. • This pump keeps the [Na+] inside the cell lower so that osmosis will not cause the cell to swell with water.

  24. ACTIVE TRANSPORTVESICLES • Used to transport molecules that are too large to fit thru a carrier protein. • Endocytosis • Cell “eating” (phagocytosis) or cell “drinking” (pinocytosis) • Cell wraps membrane around material forming vesicle which is taken into cell • Exocytosis • For moving material out of cell • Vesicle fuses with cell membrane releasing contents outside of cell

  25. ENDOCYTOSIS • EXOCYTOSIS

  26. Endocytosis Exocytosis

  27. Active Transport Animation • http://www.brookscole.com/chemistry_d/templates/student_resources/shared_resources/animations/ion_pump/ionpump.html

  28. Review Time • http://www.learnerstv.com/animation/animation.php?ani=164&cat=biology

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