1. 1.2 Cell Transportation

2. Learning Goal To learn more about the anatomy of parts of a cell
And how material is able to move in and out of a cell via osmosis, diffusion

3. Recall – Parts of a Cell

4. Cell Membrane: Both plant and animal cells have a cell membrane
They are said to be “semi-permeable”
Who remembers what this means?
Only certain things can move in and out of the cell

6. Cell Membrane Structure
The cell membrane regulates the movement of materials from one environment to the other (inside the cell and outside of the cell)

7. Balance in Living Cells
The structure primarily responsible for maintaining balance inside a living cell is the cell membrane
The cell membrane is semi (half)-permeable, allowing some molecules to pass through it while preventing other from doing so
On both sides of the cell membrane, water is the solvent, the meeting place for all of the other chemicals
The solute is mainly the solid particles found in the mixture. On the other hand, the solvent is the liquid portion of a mixture that dissolves the solutes. When the solutes and solvent are added together, they form a solution.

8. Review: Terminology
The solute is mainly the solid particles found in the mixture
The solvent is the liquid portion of a mixture that dissolves the solutes
When the solutes and solvent are added together, they form a solution.

9. Cell Membrane Structure
The activities of a living cell depend on the ability of its membrane to:
Transport raw materials into the cell
Transport manufactured products and wastes out of the cell
Prevent the entry of unwanted matter into the cell
Prevent the escape of the matter needed to perform the cellular functions

10. Cell Transport

11. Transportation in Cell Membrane
Only water and gases can easily pass through the cell membrane
This means that LARGE and charged molecules cannot cross the cell membrane without help of other structures

12. Cell Transport
Simple Diffusion

13. Simple Diffusion Passive form of transport in a cell
It is the movement of molecules from a high concentration to an area of low concentration
Many small, uncharged molecules like Oxygen can move easily through the cell membrane this way
The difference in concentrations between these regions is called the concentration gradient
Over short distances, diffusion works well to transport small molecules across the cell membrane. For example, oxygen and carbon dioxide cross the cell membrane by diffusion. As a cell uses up dissolved oxygen, more oxygen enters the cell; as a cell generates carbon dioxide, more carbon dioxide leaves the cell.
Diffusion also explains how molecules move around once inside the cell. But the concentration gradient within a cell is not nearly as great as that across the cell membrane. Once molecules have diffused through the membrane, their rate of diffusion slows down abruptly.
Video:

14. Osmosis: The Diffusion of H2O
Osmosis: the diffusion of the solvent across a semi-permeable membrane as water moves from high [ ] to low [ ]
The direction depends on the [ ] of water on either side of the cell membrane
hypertonic- Solute concentration greater (outside cell) extracellular fluid. water goes from the inside to outside  swelling occurs maybe even hemolysis depending on the situation (plasmolysis or crenation)  hypotonic- solute concentration greater (inside cell) intracellular fluid. water goes from outside to inside  cell shrinkage observed 

15. Osmosis: The Diffusion of H2O
When the [water] outside the cell is equal to the [water] inside the cell, this is known to be called an Isotonic condition

16. Osmosis: The Diffusion of H2O
When there is more [water] outside the cell than inside the cell, then this is said to be a Hypotonic condition

17. Osmosis: The Diffusion of H2O
When the [water] outside the cell is LESS than [water] inside the cell, it is said to be a Hypertonic condition

19. Osmosis: The Diffusion of H2O
The cell membrane cannot prevent this movement of water
Because it is permeable to water molecules
Therefore, osmosis (like diffusion) is a passive process that does not require energy from the cell
In essence, all atoms, ions, and molecules are in constant random motion, even those within a solid. The molecular motion in solids is not very much - the molecules simply vibrate in place, but they do have motion. This is the Bownian effect - A key word in this phenomenon is random motion

20. Gizmo!
Osmosis Lab Time!