DIFFUSION & OSMOSIS. Cell membranes are permeable (having pores or openings) to water, therefore,...
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Transcript of DIFFUSION & OSMOSIS. Cell membranes are permeable (having pores or openings) to water, therefore,...
DIFFUSION&
OSMOSIS
Cell membranes are permeable (having pores
or openings) to water, therefore, the environment the cell is exposed to can have a dramatic effect on the cell.
Cell Membranes
MembraneComposition
Lipids
Proteins
Question:How are the materialsarranged?
Plasma membrane
Question
How do materials get acrossa cell's membrane?
•Passive Transport
•Active Transport
Passive Transport
Movement acrossmembranes that does NOTrequire cellular energy.
DIFFUSION
Molecules move from areas of higher
concentrations to areas of lower concentrations
Equilibrium
When the concentration isequal on both sides.
There is no net movement ofmaterials.
Factors that EffectDiffusion
1. Concentration
2. Temperature
3. Pressure
4. Particle size
5. Mixing
Osmosis: the movement of water molecules from an area of high concentration to an area of low concentration.
OSMOSIS
Tonicity
The concentration of waterrelative to a cell.1. Isotonic (same)
2. Hypotonic (below)
3. Hypertonic (above)
Isotonic : contains the same concentration inside & outside the cell. Water diffuses into & out of cell at the same rate.
Isotonic
Hypotonic contains a low concentration)The water diffuses into the cell, causing the cell to swell and possibly explode.
Hypotonic
Hypertonic : contains a high concentration The water diffuses out of the cell, causing the cell to shrivel.
Hypertonic
Active Transport
Movement acrossmembranes that DOESrequire cellular energy.
Forming vesicles
Question?
How does the cell membrane know what to let in and what to let out?
SELECTIVE PERMEABILITY
SELECTIVE PERMEABILITY
Summary
Know membrane structure.
Be able to discuss thevarious methods by whichcells move materials throughmembranes.
Be able to solve problems inosmosis.
You should know & be able to explain the following points:
•Diffusion•Osmosis
•Passive & Active
Transport
•Selective Permeability
•Membrane structure