1. 1 Cell Transport copyright cmassengale

2. Check Your Understanding At the end of today’s lesson, you should be able to answer the following questions: What are the parts of the cell membrane and what do they do? What is the “Fluid Mosaic Model?” Describe the processes of diffusion, osmosis, facilitated diffusion, and active transport.

3. Cell Membrane copyright cmassengale3 Regulates passage of materials into and out of the cell Parts of the membrane: A) lipid bilayer (2 layers) B) proteins C) cholesterol D) carbohydrate chains

4. Lipid Bilayer Made of 2 sheets of phospholipids, a type of lipid with a head and 2 tails Hydrophilic (water loving) head Hydrophobic (water fearing) tail copyright cmassengale4

5. Why do the phospholipids arrange themselves in a bilayer? copyright cmassengale5

6. Membrane Proteins: Act as channels for large particles to enter and leave the cell Fluid-Mosaic Model: describes the flexibility of the lipid bilayer with a mosaic of proteins and other molecules 6..\..\..\Downloaded Videos\Fluid mosiac model.avi

7. Carbohydrate Chains Recognize parts of molecules to determine what molecules can be brought into the cell Can be attached to proteins or phospholipids Lock and Key Fit!

9. Label the Parts of the Membrane! Outside cell Inside cell Phospholipid Protein Carbohydrate Chain

10. Function of the Cell Membrane Regulates what enters and leaves the cell Provides protection and support

11. Random Transition…AHHHH! This may seem completely rando…but I promise the dots will connect later!

12. Concentration In a solution, the concentration is the mass of solute in a given volume of solution A difference in concentration over a distance is called a concentration gradient

13. 13 Simple Diffusion HIGH to LOWDescription: Molecules move from area of HIGH to LOW concentration This means they are going DOWN the CONCENTRATION GRADIENT PASSIVE Process (no energy required)

14. 14..\..\..\Downloaded Videos\Diffusion.avi

15. Simple Diffusion of a Solute Across a Membrane copyright cmassengale15

16. Can all solutes cross the membrane by simple diffusion? NO! The membrane is selectively permeable, this means only certain solutes (typically small ones) can pass across by simple diffusion The solution? – Channel Proteins! copyright cmassengale16

17. Facilitated Diffusion Description: Diffusion of certain molecules through a selectively permeable membrane, made possible by protein channels PASSIVE Process DOWN gradient..\..\..\Downloa ded Videos\facilita ted diffusion.avi

18. 18 Osmosis Description: Diffusion of WATER across a selectively permeable membrane PASSIVE process DOWN GRADIENT (that is, WATER moves down its gradient)..\..\..\Downloaded Videos\Osmosis.avi

19. Cell in Isotonic Solution CELL 10% solute 90% water 10% solute 90% water What is the direction of water movement? The cell is at EQUILIBRIUM. ENVIRONMENT Solution outside the cell has the SAME solute (and water) concentration as the cell itself

20. 20 Cell in Hypotonic Solution CELL 10% solute 90% water 20% solute 80% water What is the direction of water movement? ENVIRONMENT Solution outside the cell has a LOWER solute (HIGHER water) concentration than the cell itself

21. 21 Cell in Hypertonic Solution CELL 15% solute 85% water 5% solute 95% water What is the direction of water movement? ENVIRONMENT Solution outside the cell has a HIGHER solute (LOWER water) concentration than the cell itself

22. Isotonic Solution NO NET MOVEMENT OF H 2 O (equal amounts entering & leaving) Hypotonic Solution Cell Bursting Hypertonic Solution Cell Shrinking..\..\..\Downloaded Videos\Onion Cells Plasmolysis.avi..\..\..\Download ed Videos\Red Blood Cells in Hypotonic Solution.avi..\..\..\Downloaded Videos\Red Blood Cells in a Hypertonic Solution.avi

23. 23 Osmosis in Red Blood Cells Isotonic Hypotonic Hypertonic copyright cmassengale

24. Osmosis in Plant Cells

25. Active Transport Description: Movement of materials from LOW to HIGH concentration ACTIVE process (uses energy) UP Concentration Gradient

26. Active Transport Molecular Pumps ATP Molecular pumps are membrane proteins that use energy from ATP to move molecules across cell membranes. (Each pump moves one type of molecule)..\..\..\Downloaded Videos\Active Transport.avi

27. Endocytosis vs. Exocytosis Endocytosis: taking large amounts of material into the cell Exocytosis: sending large amounts of material out of the cell copyright cmassengale27

28. Endocytosis: Phagocytosis & Pinocytosis Phagocytosis: The membrane folds to enclose solid particle (cell eating) Pinocytosis: The membrane folds to enclose liquid with dissolved materials (cell drinking)

29. In endocytosis, the membrane pinches in to form a vesicle The vesicle may later join with a lysosome so that particles can be “digested” copyright cmassengale29 Vesicles

30. Exocytosis 1 Products of the ER are packaged in vesicles at the Golgi and released at the cell membrane...\..\..\Downloaded Videos\Endocytosis & Exocytosis.avi

31. Cell Membrane and Homeostasis Refresher from Characteristics of Life…what is homeostasis? How does the cell membrane help organisms to maintain homeostasis?