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Chapter 7.3 Cell Transport

Chapter 7.3 Cell Transport. Warm-Up. What do you know so far about the cell membrane? What do you want to know about the cell membrane?. Cell Membrane Structure & Function. Phospholipid Bi-layer (hydrophilic heads, hydrophobic tails) Fluid-Mosaic Model

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Chapter 7.3 Cell Transport

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  1. Chapter 7.3Cell Transport

  2. Warm-Up What do you know so far about the cell membrane? What do you want to know about the cell membrane?

  3. Cell Membrane Structure & Function • Phospholipid Bi-layer (hydrophilic heads, hydrophobic tails) • Fluid-Mosaic Model • Proteins & cholesterol embedded within the phospholipid bi-layer • Selectively Permeable – controls was enters and exits the cell

  4. Fluid-Mosaic Model • Channel Proteins: • Allow molecules, such as water, to pass through the cell membrane • Recognition/ID Protein: • Has carbohydrate chains attached that are used as ID markers • Allow cells to communicate with eachother and identify foreign invaders (other blood type, virus)

  5. Fluid-Mosaic Model • Protein Pump: • Use ATP (energy) to pump substance across the membrane • Cholesterol: • Lipid that controls the fluidity of the cell membrane

  6. Cell membrane transport • There are 2 types of cell membrane transport: • Passive Transport • Things flow from High to low • Active Transport • Things flow from Low to high

  7. Another perspective on passive and active transport

  8. Passive Transport • Diffusion • The movement of particles from areas of high concentration to low concentration • http://www.indiana.edu/~phys215/lecture/lecnotes/diff.html • http://www.biosci.ohiou.edu/introbioslab/Bios170/diffusion/Diffusion.html

  9. Equilibrium • When is equilibrium reached when discussing cell membrane transport? • When the concentrations of particles are the same on both sides

  10. Facilitated Diffusion • Particles flow from high concentration to low concentration but this time they need the help of proteins to get through the cell membrane.

  11. Facilitated diffusion

  12. Passive transport • Osmosis • The diffusion of water across a selectively permeable membrane • Important in maintaining cell homeostasis • Water flows to side of membrane where the water concentration is lower until equilibrium is reached

  13. Osmosis • Osmosis is controlled by the amount of solutes on either side of a membrane

  14. Osmosis – Types of Solutions • When dealing with osmosis, water can either move into the cell or out of it. • The solute can not move to equal out the solution so the water has to. • We describe the solutions that cells are in as either hypotonic, isotonic, or hypertonic. 90% What are the concentrations? 40%

  15. Isotonic Solution • Isotonic solution – Concentration of solute is the same in the cell and the area around the cell. • Give me an example of an isotonic solution that some of you use everyday

  16. Isotonic solution

  17. Hypotonic Solution • Hypotonic Solution – Concentration of solute is lower in the solution than in the cell. • Where is water going to move in order to reach equilibrium (Equal concentrations)? • Inside the cell

  18. Hypotonic solutions • Since water moves into the cell the cell can explode • http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm • So, Hypotonic solution, low concentration of solute, cell can explode

  19. Plant and animal cells in a hypotonic solution

  20. Hypertonic Solution • Hypertonic solution – concentration of solute is higher in the solution than in the cell. • Where is water going to move in order to reach equilibrium (Equal concentrations)? • Outside the cell

  21. Hypertonic solutions • Since water moves out of the cell the cell will shrink • http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm • So, Hypertonic solution, high concentration of solute, cell will shrink

  22. Plant and animals cells in a Hypertonic Solution

  23. Osmosis • http://www2.nl.edu/jste/osmosis.htm • http://www.coolschool.ca/lor/BI12/unit4/U04L06/rbc.html

  24. Active Transport • Molecules move from low concentration to high concentration • Requires energy….why?

  25. Active Transport • Molecular Transport – • Protein Pumps • Small molecules and ions carried across the cell membrane by proteins in the membrane that act like pumps • Bulk Transport • Endocytosis – in! • Exocytosis – out!

  26. Other membrane transport activities that require energy • Endocytosis • Engulfing of large particles or liquids from outside the cell

  27. 2 types of Endocytosis • Phagocytosis • Engulfing of large particles from outside the cell • Pinocytosis • Engulfing of liquids from outside the cell

  28. Other membrane transport activities that require energy • Exocytosis • Release of large particles or liquids from inside the cell Outside the cell Inside the cell

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