1. Homeostasis and Transport
Movement of cellular materials in and out of the cell.

2. Cell membranes help cells maintain homeostasis by controlling what substances may enter or leave cells.

3. Cell membranes are selectively-permeable in that they allow only certain substances to pass.

4. I - Passive Transport No energy input from the cell.
No ATP energy molecules used.

5. Simplest type of Passive Transport: (simple) Diffusion
It is the (random) movement of molecules from an area of higher concentration to an area of lower concentration.

6. In other words…
Materials move from where there’s more to where there’s less.

7. This difference in concentration of molecules (over a given area)is called the concentration gradient
Diffusion movement occurs with, (or down) the concentration gradient.

8. Diffusion is driven by the kinetic energy of the molecules.

9. Kinetic Energy – Energy of Movement
from an
area of
low to
high
concentration

10. Eventually the process of diffusion reaches equilibrium.
At equilibrium the concentration of molecules are the same throughout the space. (The concentration gradient disappears)

11. Are the molecules still moving at this point (equilibrium)?
Yes. Molecules of a substance are always in motion to some degree except at absolute zero.
The net movement is zero.

13. Osmosis
The process by which H2O molecules diffuse across a cell membrane (selectively permeable membrane) from an area of HIGH concentration to LOW concentration.

14. The net direction of water movement depends on the relative amount of solutes (dissolved substances) on the two sides of the cell membrane.

15. THE THREE BASIC TYPES OF SOLUTIONS:
Hypotonic
Hypertonic
Isotonic

16. Hypotonic
solute concentration outside the cell is lower than inside the cell cytosol.
water diffuses into the cell

17. Hypertonic
solute concentration outside the cell is higher than inside the cell cytosol.
water diffuses out of the cell

18. Isotonic
solute concentration outside and inside the cell are equal thus, NO net movement of water into or out of the cell

19. How do cells deal with osmosis?
Isotonic – usually no difficulties
interesting chromosome
pattern makes this
cell have a happy
face

20. Hypotonic environment
Unicellular freshwater organisms rid themselves of excess water by an organelle called a contractile vacuole. (Other cells cannot get rid of the water and they may burst)

21. What happens to an
animal cell under
different conditions?

23. What happens to a
plant cell under
different
conditions?

25. Facilitated Diffusion
It is a type of passive transport in which molecules pass through pores in the cell membrane. Carrier proteins help move molecules across the membrane.

26. II - ACTIVE TRANSPORT ATP Cell expend energy to move materials.
Active transport always needs ATP energy molecules
ATP

27. Active Transport is usually against the concentration gradient.
Materials move from low to high concentration.

28. EXAMPLES OF ACTIVE TRANSPORT
Cell Membrane Pumps (such as the Sodium-Potassium pump) It involves Carrier proteins
Sodium-Potassium Pump is important for nerve cells.

29. Endocytosis - cells take in fluids, large molecules, large particles and other cells.
Vesicles are formed to ingest materials.

30. Two major types of endocytosis:
pinocytosis – movement of solutes or fluids
(Cell-drinking)

31. phagocytosis – movement of large particles or whole cells
phagocytosis – movement of large particles or whole cells. (cell-eating)
Amoeba uses pseudopodia to engulf food.

32. Exocytosis (the reverse of endocytosis)
Vesicles fuse with the cell membrane, releasing their contents to the outside environment.

33. Unicellular organisms may get rid of wastes through exocytosis.