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9/19 Warm Up

9/19 Warm Up. What is the theory that states that prokaryotic cells further developed eukaryotic cells? Endosymbiotic theory. What are the names of the two electron microscopes? (Give abbreviations) TEM-Transmission Electron Microscope SEM-Scanning Electron Microscope. Section 4.

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9/19 Warm Up

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  1. 9/19 Warm Up What is the theory that states that prokaryotic cells further developed eukaryotic cells? Endosymbiotic theory What are the names of the two electron microscopes? (Give abbreviations) TEM-Transmission Electron Microscope SEM-Scanning Electron Microscope

  2. Section 4 Cellular Transport

  3. Video • http://player.discoveryeducation.com/index.cfm?guidAssetId=2856C74B-9BC5-4D13-AF58-367F4FE3179D&blnFromSearch=1&productcode=US • Diffusion & Osmosis • http://player.discoveryeducation.com/index.cfm?guidAssetId=9F4BCA98-9CE4-402C-9F57-E3C871343CA9&blnFromSearch=1&productcode=US • Dynamic Equilibrium

  4. Plasma membrane can act like a dam that lets water out without spending energy… Or it can act like a hand pumped well with uses energy to move water- soluble molecules.

  5. Diffusion Diffusion is the movement of particles from an area where there are many particles of a substance to an area where there are fewer particles of a substance. Substances diffuse from areas of high concentration to low concentration. No energy is used due to the fact that the particles are already moving.

  6. Active Transport Sometimes substances move from a region of lower concentration to a region of high concentration against the passive movement of high to low. Some active transport pumps move one type of substances in one direction, while others move 2 substances in the same or opposite directions. Requires energy!

  7. How Active Transport Works • Carrier protein binds with particle to be transported • Protein & molecule fit like puzzle pieces, they’re specificto each other • Once bound, protein changes shape to deposit molecule on other side of membrane • Then it goes back to its original shape

  8. Passive Transport Passive transport movement of particles across membranes by diffusion Uses no energy H2O, lipids, & lipid-soluble substances can cross P.M.

  9. Passive & Active Transport compared

  10. Diffusion across the plasma membrane • Water can diffuse across the plasma membrane, but most other substances cannot. • Facilitated diffusion. • Uses transport proteins to move other ions and small molecules across the plasma membrane. • Substances move into the cell through a water-filled transport protein called a channel protein that opens and closes to allow the substance to diffuse through the plasma membrane. • Carrier proteins • These proteins helps substances diffuse across the plasma membrane

  11. Diffusion (Dynamic Equilibrium) • Dynamic Equilibrium occurs when particles continue to move randomly, but no further change in concentration will occur. • 3 Main factors affect the rate of diffusion: • 1. Concentration • 2. Temperature • 3. Pressure • As you increase these three things, so does the process of diffusion.

  12. Osmosis: Diffusion of Water The diffusion of water across a selectively permeable membrane. Osmosis is important because it maintains the homeostasis of the cell.

  13. How Osmosis Works Solution: contains solute and solvent. Solute: substance Solvent: liquid solution The concentration of a solution decreases when the amount of solvent increases. Water molecules diffuse toward the side with the greater solute concentration. The water continues to diffuse until dynamic equilibrium takes place.

  14. Cells in Isotonic Solutions A cell in an isotonic solution has the same concentration of water and solutes—ions, sugars, proteins—in its cytoplasm as the fluid around it. Iso- comes from the Greek word equal. Water enters & leaves the cell at the same rate.

  15. Cells in isotonic solution don’t experience osmosis & retain normal shape

  16. Cells in Hypotonic Solutions A hypotonic solution has a lower concentration of solute (more solvent, water) than the cell’s cytoplasm. Hypo comes from the Greek word under. Water diffuses into the cell causing the membrane of the cell to swell, which could possibly cause the cell to burst.

  17. Plant cells have rigid cell wall so they don’t burst from this As pressure increases, plasma membrane gets pressed against cell wall

  18. Plant cell in isotonic solution

  19. Plant cell in hypotonic solution

  20. This actually makes plant cells more firm • This reaction is why veggies are misted!

  21. Cells in Hypertonic Solutions Hypertonic solutions occur when the concentration of the solute outside the cell is higher than the inside (less water outside the cell). Hyper comes from the Greek word above. Water diffuses out of the cell and cells shrivel because of the decreased pressure.

  22. Don’t salt meat before cooking! • Plant cells will lose H2O from vacuole • Cytoplasm & plasma membrane shrink from cell wall

  23. Loss of H2O results in drop in pressure = wilt!

  24. Transport of Large Particles • Some substances that are too large to move through the plasma membrane go through a different process. • Endocytosis: • Substances are taken into the cell • Exocytosis: • Substances are expelled or secreted out from the cell • Both require E • Both forms of active transport

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