1. Cell Membrane & The Ways Molecules Move

2. Cell Membrane & The Ways Molecules Move
I. Cell Membrane
1) POLAR ends face INSIDE & OUTSIDE cell [where water is]
2) NONPOLAR tails face each other inside bilayer [to avoid water]
Cell Membrane & The Ways Molecules Move

3. Cell Membrane & The Ways Molecules Move
Outside
of cell
Inside
(cytoplasm)
Cell
membrane
Proteins
Protein
channel
Lipid bilayer
Carbohydrate
chains
Cell Membrane & The Ways Molecules Move 3

4. Cell Membrane & The Ways Molecules Move
II. FUNCTION: SELECTIVE PERMEABILITY = allows only certain materials to go into & out of cell
Cell Membrane & The Ways Molecules Move 4

5. Cell Membrane & The Ways Molecules Move
a. Why doesn’t the cell membrane let everything through?
HOMEOSTASIS!
- Cells maintain a stable environment by controlling what enters & leaves.
Cell Membrane & The Ways Molecules Move

6. III. Cellular Transport – Two Major Types (Passive & Active Transport)
Cell Membrane & The Ways Molecules Move
Passive Transport = moves molecules across cell mem. using NO ENERGY
Movement going with the concentration gradient (normal flow)
Cell Membrane & The Ways Molecules Move

7. Cell Membrane & The Ways Molecules Move
A. Types of Passive Transport
Diffusion – molecules move from HIGH conc. to LOW conc.
a. Small molecules: O2, CO2
b. Slow process
Cell Membrane & The Ways Molecules Move

8. Cell Membrane & The Ways Molecules Move

9. Cell Membrane & The Ways Molecules Move

10. Cell Membrane & The Ways Molecules Move
2. Facilitated Diffusion – movement of molecules with help of a carrier protein
Cell Membrane & The Ways Molecules Move

11. Cell Membrane & The Ways Molecules Move

12. Cell Membrane & The Ways Molecules Move
Moves large molecules
like Glucose and Fructose (C6H12O6)
b. Faster than diffusion
Cell Membrane & The Ways Molecules Move

13. Cell Membrane & The Ways Molecules Move
Cell Membrane & The Ways Molecules Move

14. Cell Membrane & The Ways Molecules Move
3. Osmosis – diffusion of WATER across cell membrane
* H2O moves to area with LESS WATER
Cell Membrane & The Ways Molecules Move

15. Cell Membrane & The Ways Molecules Move
a. Direction of Osmosis:
1) Hypotonic Solution = H2O moves INTO cell & CELL EXPANDS
Cell Membrane & The Ways Molecules Move

16. Cell Membrane & The Ways Molecules Move
2) Hypertonic Solution = H2O moves OUT OF cell & CELL SHRINKS
Cell Membrane & The Ways Molecules Move

17. Cell Membrane & The Ways Molecules Move
3) Isotonic Solution = H2O moves INTO & OUT OF cell & cell stays NORMAL SIZE
Cell Membrane & The Ways Molecules Move

18. Cell Membrane & The Ways Molecules Move

19. Cell Membrane & The Ways Molecules Move
* EQUILIBRIUM = concentration of molecules is same everywhere
* Molecules never stop moving – even at equilibrium
Cell Membrane & The Ways Molecules Move

20. PROBLEM for Cells? Cell membranes are SELECTIVELY PERMEABLE

21. 2. 2nd Type of Transport  Active Transport
moves molecules across cell membrane using ENERGY

22. Cell Membrane & The Ways Molecules Move
B. Types of Active Transport
Cell Membrane & The Ways Molecules Move
1. Transport Proteins: in membrane- move substances from low to high conc. (opposite of how it wants to move)
Cell Membrane & The Ways Molecules Move

23. 2. Endocytosis = cell surrounds & ingests materials from OUTSIDE to INSIDE cell using VESICLES

24. Cell Membrane & The Ways Molecules Move
Cell Membrane & The Ways Molecules Move

25. Cell Membrane & The Ways Molecules Move
a. Steps:
1) membrane folds in & forms pocket
2) Pocket closes & pinches off in cell vesicle
3) vesicle fuses w/ organelles to release contents
Cell Membrane & The Ways Molecules Move

26. Cell Membrane & The Ways Molecules Move
b. Two Types of Endocytosis:
Phagocytosis – LARGE particles (food) or whole CELLS (bacteria) into cell
2) Pinocytosis – large amounts of liquids/ fluids into cell
Cell Membrane & The Ways Molecules Move

27. Cell Membrane & The Ways Molecules Move
3. Exocytosis –releases large amounts of material to the OUTSIDE of the cell using VESICLES
Cell Membrane & The Ways Molecules Move

28. Cell Membrane & The Ways Molecules Move
a. Steps:
Vesicle forms, travels to & fuses w/ cell mem.
Vesicle opens to outside & releases contents
Cell Membrane & The Ways Molecules Move

29. Cell Membrane & The Ways Molecules Move
Cell Membrane & The Ways Molecules Move