1. Cell Processes

2. The Cell Membrane
The membrane that surrounds the cell and its organelles.
Acts as a gateways between the outside environment and a cell’s cytoplasm.
Selectively permeable – allow only certain substances in and out of the cell, not all substances.

3. Solutions
Substances entering and leaving a cell, through the cell membrane, are dissolved in a liquid – solution.
Solutions are mixtures of two or more substances.
Substance that does the dissolving = solvent.
Water is the universal solvent.
Substance that is being dissolved = solute.

4. Solvent = water
Solute = sugar
Solution

5. Concentrations
The amount of substances being dissolved compared to the amount of substance doing the dissolving = concentration.
High concentration = high solute, little solvent
Ex. Very sweet lemonade = lots of mix (solute), little water (solvent)
Low concentrations = little solute, high solvent
Ex. Weak tasting lemonade = small amount of mix (solute), lots of water (solvent)

6. Cell Transport
Substances are transported into or out of a cell in two ways:
Passive Transport – No energy is required to move the substances.
Active Transport – Energy IS required by the cell to move the substances.
BrainPop – Active Transport

7. Passive Transport
Cells move materials from areas of high concentration to areas of low concentrations – concentration gradient.
Depending on the substance being moved, transport occurs in two ways:
Diffusion = movement of particles
Osmosis = movement of water

8. Diffusion
When particles in a solution are in constant motion, colliding, causing them to spread out.
continue to move until concentration is the same = Equilibrium.
Examples:
Oxygen moving from your lungs to your bloodstream
Carbon dioxide moving from your bloodstream to your lungs
Nutrients moving from your small intestine into your bloodstream.

9. Equilibrium

10. Diffusion Through a Membrane
Process of Diffusion – animation

11. Osmosis - Passive
The movement of water into or out of the cell from regions of high concentration to regions of low concentration - Osmosis.
Perhaps the most important substance that passes through the cell membrane is WATER.
Cells can’t function properly without adequate amount of water.
BrainPop – Passive Transport

12. Osmosis
Water is at equilibrium!

13. Three solution types: Osmosis
Hypertonic Solution – higher water concentration inside the cell than outside
Water will move out of the cell = shrink

14. Three solution types: Osmosis
2. Hypotonic Solution – higher water concentration outside the cell than inside.
Water will move into the cell = swell

15. Three solution types: Osmosis
Isotonic Solution – equal concentrations of water inside and outside the cell.
a. Water moves equally in and out of the cell.

16. Osmosis in Blood Cells
Isotonic
Hypotonic
Hypertonic

17. Active Transport
Some materials must be moved against the concentration gradient by active transport.
Energy IS required!
Two Methods:
Molecule Transport
The use of proteins in the membrane to move substances across the membrane.

18. Cell Transport – Active Transport
Endocytosis and Exocytosis
Some cells take in or release materials through movements of the cell membrane using energy.
Exocytosis