Types 1) Diffusion = movement of molecules from high to low [ ] (concentration) - driven by the concentration gradient - spreads out evenly till dynamic equilibrium is reached - spreads out evenly till dynamic equilibrium is reached
2) Osmosis = diffusion of water A solution may be one of the following: (compared to a cell) - isotonic solution: same [ ] of water and solute - hypotonic solution: lower [ ] of solute, a lot of water - hypertonic solution: higher [ ] of solute, less water
Isotonic Solution (Red Blood Cells) A solution is isotonic to a cell if it has the same concentration of solutes as the cell. Equal amounts of water enter and exit the cell, so its size stays constant.
Hypotonic Solution (Red Blood Cells) A hypotonic solution has fewer solutes than a cell. Overall, more water enters a cell in a hypotonic solution, causing the cell to expand and even burst.
Hypertonic Solution (Red Blood Cells) A hypertonic solution has more solutes than a cell. Overall, more water exits a cell in a hypertonic solution, causing the cell to shrivel and even die
Direction of Osmosis Outside the Cell Inside the Cell Net Movement of Water Isotonic Isotonic None Isotonic Isotonic None Hypotonic HypertonicInside the Cell Hypotonic HypertonicInside the Cell Hypertonic Hypotonic Outside the Cell Hypertonic Hypotonic Outside the Cell ** If the solution outside the cell is hypotonic, then inside the cell is hypertonic and vice versa ** Water tends to diffuse from hypotonic to hypertonic
- Plasmolysis = cells shrink when turgor pressure is lost - the reason plants wilt
- Cytolysis = cell bursts due to water entering the cell