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Movement of
Materials
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Plasma Membrane(aka Cell Membrane)
• Phosopholipid Bilayer
• Called the Fluid Mosaic Model
• Selectively Permeable
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Selectively Permeable
If a membrane is selectively permeable only
certain things can pass through
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The Cell Membrane is Selective:
• Things that passively cross: – Non-Polar Molecules (Alcohols, Steriods)
– Small Molecules (Water)
• Things that actively cross: – Polar Molecules (Ions)
– Large Molecules
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Active (requires NRG)
Passive (no NRG)
Types of Transport
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Osmosis
Passive
Passive Transport
Diffusion
Facilitated Diffusion
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Passive TransportMovement of
materials that DOES NOT require energy
(ATP)
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What is happening here???
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DIFFUSIONThe passive movement
of material from an area of high concentration to
an area of low concentration
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ConcentrationThe number of a
substance in a specific area
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High Concentration
Low Concentration
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Pass
ive
Tra
nspo
rt
High Concentration
Low Concentration
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Factors Affecting Diffusion• Concentration—diffusion always goes
from high concentration to low concetration
• Temperature—the higher the temperature, the faster diffusion occurs
• Molecular Size—the bigger the molecule, the longer diffusion takes
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OSMOSISThe diffusion of water through a selectively
permeable membrane
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Osmosis—another look…
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Osmotic PressureThe force (pressure) produced by water moving into a cell
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Isotonic SolutionNo net movement of water in or out of the
cell
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Hypotonic Solution
Water moves from the solution into the cell causing it to swell or
break (lysis)
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Hypertonic Solution
The water moves out of the cell into the
solution, causing the cell to shrink
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Types of Solutions
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Why doesn’t the plant cell undergo lysis?
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WHITEBOARDINGIn your groups draw what the cells would look like in
each case.Effect of Osmosis on Cells
Animal Cell
Solution Before After
Isotonic
Hypotonic
Hypertonic
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Explain what is
happening in this
cartoon…
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Facilitated Diffusion
Diffusion that is helped by proteins in
the membrane
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Facillitated Diffusion
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Diffusion vs. Facillitated Diffusion
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MembraneMovements
Active
Active Transport
Pumps
Endocytosis Exyocytosis
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Active TransportMovement of materials
from low concentration to high concentration using a
protein carrier that requires energy
(costs ATP)
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Active T
ransportHigh Concentration
Low Concentration
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What was ATP again???
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Sodium-Potassium Pump
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EndocytosisProcess of bringing
particles into a cell using extensions of the cellular
membrane
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ExocytosisProcess of moving particles
out of a cell using extensions of the cellular
membrane (how wastes are excreted
from cells)
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Endocytosis y Exocytosis
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PhagocytosisThe process of
membrane folding that enables cells to bring “food” into the cell
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PinocytosisThe process of
membrane folding that enables cells to bring “water” into the cell