diffusion osmosis for moodle
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TRANSCRIPT
Diffusion
• Particles are always moving
• Particles move from areas of high concentration to low concentration
• Particles move until equilibrium is reached
• Particles move passively– No energy (ATP)
required– PASSIVE TRANSPORT
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html
Proteins
Recall the structure of the cell membrane…
• Selectively permeable = semipermeable– Regulates what enters and exits the cell
• Lipid bilayer (two layers of lipids = fats)• “Mosaic Model”
– Contains many types of proteins, pumps, channels, and receptors
Inside of cell (cytoplasm)
Outside of cell
Proteinchannel Lipid bilayer
Carbohydratechains
Diffusion Across the Cell Membrane
Diffusion Across the Cell Membrane
• Cell membranes are selectively-permeable - they allow some materials to pass across, but not others
(also called semipermeable)• If the membrane is permeable to a substance,
movement of that substance (solute) will occur as shown in the diagram below:
Facilitated Diffusion
• Facilitated Diffusion– No energy required – PASSIVE TRANSPORT– Uses a protein channel in the membrane
• Molecules move from high to low concentration
HighConcentration
LowConcentration
CellMembrane
Glucosemolecules
Proteinchannel
Osmosis
• Diffusion of water through a selectively permeable membrane (Osmosis is a form of facilitated diffusion.)
• PASSIVE TRANSPORT
The Effects of Osmosis on CellsAs a result of osmosis, cells respond differently when the water concentration inside the cell is equal to, greater than, or less than the water concentration in the environment.
Isotonic HypertonicHypotonic
Molecule tobe carried
Moleculebeing carried
Energy
Active Transport
• Requires energy• Moves materials from
area of LOW to HIGH concentration (against a concentration difference)
Active Transport
Diffusion, Osmosis, Facilitated Diffusion, or Active Transport?
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Diffusion, Osmosis, Facilitated Diffusion, or Active Transport?
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