cell transport osmosis and diffusion. particles in constant motion run into each other and...
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Cell Transport
Osmosis and Diffusion
Particles in constant motion Run into each other and randomly spread out
Particles move from an area of high concentration to an area of low concentration
Diffusion
Diffusion Can occur across membranes IF the particle
can cross the membrane
Does not require energy Passive transport
Time
Semipermeable
Facilitated Diffusion Molecules that can’t pass directly through
membrane may pass through a protein channel in membrane
Still no energy = passive transport
Osmosis Specific type of facilitated diffusion Diffusion of water through a selectively
permeable membrane
Is energy required?
Osmosis, cont’d Water moves from an area of high concentration to an area of
low concentration.
When comparing two solutions: Hypotonic – “below strength”; lower concentration of solute, higher
concentration of water Hypertonic – “above strength”; higher concentration of solute, lower
concentration of water Isotonic – “same strength”; solutions have same concentration of
solute and same concentration of water
Osmosis, cont’d Water moves from an area of high
concentration to an area of low concentration.
1 % salt99%
water
0% salt100%
water
In which direction will water move? Into the cell our out of the cell?
Water moves into cell(trying to reach equilibrium)
What will happen to the cell?
Is the solution hypertonic, isotonic, or hypotonic?
Hypotonic Solution
Osmosis, cont’d Water moves from an area of high
concentration to an area of low concentration.
1 % salt99%
water
5% salt95%
water
In which direction will water move? Into the cell our out of the cell?Water moves out of the cell.
What will happen to the cell?
Is the solution hypertonic, isotonic, or hypotonic?
Hypertonic Solution
Osmosis, cont’d Water moves from an area of high
concentration to an area of low concentration.
1 % salt99%
water
1% salt99%
water
In which direction will water move? Into the cell our out of the cell?No net movement of water!
What will happen to the cell?
Is the solution hypertonic, isotonic, or hypotonic?
Isotonic Solution
Active Transport Allows movement of particles against the
concentration gradient In other words, particles can move from low
concentration to high concentration
Proteins in membrane “pump” the molecules in or out
Requires energy Active transport
Passive vs. Active Transport