Download Osmosis Diffusion Notes

Cell Membarane
• Also known as
Plasma Membrane
and Phospholipid
Bi-layer
• Defines the shape of
the cell.
• Maintains
Homeostasis
(controls what goes in
and out)
What is the cell membrane made
of?
• Phosphate HeadPolar so always
points toward water
(Hydrophilic)
• Lipid TailsNon-polar so always
point away from water
(Hydrophobic)
(Blood)
(Cytoplasm)
1. Channel Protein- tunnel in and out. Can be gated to open
and close. Use energy to go against concentration (active
transport) and do not use energy to go with concentration
(passive transport)
2. Receptor Protein- receives chemical signals from the
blood and communicates them to the inside of the cell.
3. Glycoprotein + Carbohydrate- identifies the cell so it will
not be destroyed.
Key Words
• Solution- combination of a solute and a
solvent.
• Solute- Substance that is dissolved in a
solvent (i.e. salt, sugar etc)
• Solvent- Substance that other substances
are dissolved into (i.e.- water)
• Concentration Gradient- Difference in
solute concentration from one side of the
membrane compared to the other.
Diffusion
• Movement of a solute within a solvent from
high concentration to low concentration
• EXAMPLE- Food coloring (Solute) moving from
the high concentration of a drop to the low
concentration of the water (Solvent).
Osmosis
• Diffusion of water through a semi-permeable
membrane
• Water is the only substance that can move
freely in an out of cells without using channel
proteins.
More Complicated Than That
Why Water Moves
• Hypertonic SolutionThe outside of the
cell has more solute
than inside the cell
• RESULT- Water
moves out and the
cell shrinks.
Why Water Moves
• Hypotonic SolutionThe outside of the
cell has less solute
than inside the cell.
• RESULT- Water
moves in and the cell
swells/bursts.
Why Water Moves
• Isotonic SolutionWhen there is an
equal amount of
solute inside and
outside the cell
• RESULT- Water
moves both in and out
of the cell at the same
rate and the cell
stays the same
Moving Stuff
Passive TransportMovement across a
cell membrane that
goes with
concentration
gradient and does
not use any energy
Examples- Osmosis
and Facilitated
Diffusion
Moving Things
• Active TransportMovement across a
membrane going
against
concentration
gradient where
energy is needed
• ExamplesEndocytosis and
Exocytosis
Endocytosis- use of vesicles to transport
large objects into the cell.
Exocytosis-use of vesicles to move large
objects out of the cell.
Sodium Potassium Pump
Active Transport
• Sodium Potassium Pump moves 3 Na+ ions out
of the cell and brings 2 K+ ions into the cell
creating + out side and a – inside.
• This is moving against concentration so it
requires ATP (Energy)
• When the nerve fires Na+ ion channels open in
the membrane and Na+ floods in changing
charge on the inside only to be reset by the
Na/K pump.
https://www.youtube.com/watch?v=PimDC1txWw&index=2&list=FLEezLUm-pa3vfMmQGp1aPTQ
https://www.youtube.com/watch?v=SdUUP2pMmQ4&index=1&list=FLE
ezLUm-pa3vfMmQGp1aPTQ