1. Diffusion and Osmosis

2. To remain alive, cells, tissues, and organs must maintain a balance between themselves and the environment. This balance is called homeostasis.

3. Homeostasis occurs from the organism level all the way down to the cellular level
At the cellular level, homeostasis often begins with diffusion and osmosis

4. Molecules are in constant motion. This motion is called Brownian motion. Molecules tend to move from areas of high concentration to areas of low concentration. This is called diffusion.

5. Examples:
Food coloring in water
Cream in coffee
Smoke in the air

6. Diffusion
Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration

7. Solutions Solutions have two parts Solute- What is being dissolved.
Solvent- The liquid in which things are being dissolved

9. Solutions
The concentration of a solution is the amount of solute in a solution or over a space
Concentration gradient is the difference in concentration of a substance over a space
Equilibrium is when the amount of substance is equal over space.

10. In other words – diffusion is the movement of particles along a concentration gradient

12. Diffusion is a type of passive transport
Passive Transport is the movement of molecules without using energy

13. Is there movement of molecules during equilibrium?

14. Diffusion across a membrane.
Some molecules move freely across membranes.
The membrane is called permeable if molecules can pass through

16. Some membranes are selectively permeable; they allow some molecules to pass through while others may not.

17. Cells have selectively permeable membranes
Cells have selectively permeable membranes. These membranes are flexible and are made from 2 layers of phospholipids
phospholipid
Phospholipid bilayer

20. Animal cells only have cell membranes
Plant cells have cell membranes and a cell wall

21. Osmosis  
Osmosis in the diffusion of water across a selectively permeable membrane
Regulating the water flow through the selectively permeable membrane of the cell is an important factor in maintaining homeostasis within a cell

24. Most cells whether in multicellular or unicellular organisms, are subject to osmosis because they are surrounded by water solutions.