1. WELCOME!
IN Question :
How do unicellular organisms maintain homeostasis when responding to various stimuli in their environment.
Give 1 example to support your answer.

2. CELL MEMBRANE: Draw and label a lipid bilayer.

3. CELL BOUNDARIES
TEKS 4B
Investigate and explain cellular processes, including homeostasis, energy conversions, transport of molecules, and synthesis of new molecules

4. Chapter
Cell membrane regulates what enters and leaves the cell and also provides protection and support
Cells in a multicellular organism develop in different ways to perform particular functions within the organism.

5. Cell Walls vs. Cell Membranes
Both provide support and protection.
Only the cell membrane regulates what enters and leaves.
The cell wall is too porous to do that.

6. Cell Membrane Regulation
The cell membrane is made out of a lipid bilayer that is semipermeable.
So….only some things go in and out.

7. Cell membrane Lipid Bilayer: Two layers of fat molecules.
Forms the cell membrane

8. Draw and label a lipid bilayer.

9. Cell Membrane Transportation
Diffusion – Molecules move from a concentrated (crowded) area to a less concentrated area to be in equilibrium.
Equilibrium – equal concentration, no net movement of molecules
Osmosis - Diffusion of water through a selectively permeable membrane

10. Diffusion

11. Is this really osmosis?

12. Hypertonic Concentration of solutes is more outside the cell than in
Water flows out of cell
The cell shrivels and may die.

13. Isotonic Concentration is the same inside and out No net movement
The cell stays the same

14. Hypotonic Concentration of solutes is less outside the cell than in.
Water flows in
The cell swells with water, becomes “turgid”, and dies.

15. Facilitated Diffusion
Helps large molecules move through protein channels found in the membrane
No energy required

16. Active Transport
Forces large molecules to move in and out through protein pumps found in the membrane
Energy is required

17. Endocytosis
Cell takes material into cell by infolding the cell membrane with vesicles
Phagocytosis – eating – cell engulfs large particles
Pinocytosis – drinking – cell takes in liquid

18. Phagocytosis
engulfing solid particles by the cell membrane

19. Exocytosis
Cell releases large amounts of material

20. Cell Specialization
The cells in multicellular organisms can develop in different ways to perform different tasks.

21. H.W. Cell Membrane & Transport Activity (See Our Course Web Links Page)

22. EXIT TICKET
OUT Question :
Explain why a freshwater fish cannot survive in a saltwater environment?