Movement of
Materials
Plasma Membrane(aka Cell Membrane)
• Phosopholipid Bilayer
• Called the Fluid Mosaic Model
• Selectively Permeable
Selectively Permeable
If a membrane is selectively permeable only
certain things can pass through
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
Active (requires NRG)
Passive (no NRG)
Types of Transport
Osmosis
Passive
Passive Transport
Diffusion
Facilitated Diffusion
Passive TransportMovement of
materials that DOES NOT require energy
(ATP)
What is happening here???
DIFFUSIONThe passive movement
of material from an area of high concentration to
an area of low concentration
ConcentrationThe number of a
substance in a specific area
High Concentration
Low Concentration
Pass
ive
Tra
nspo
rt
High Concentration
Low Concentration
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
OSMOSISThe diffusion of water through a selectively
permeable membrane
Osmosis—another look…
Osmotic PressureThe force (pressure) produced by water moving into a cell
Isotonic SolutionNo net movement of water in or out of the
cell
Hypotonic Solution
Water moves from the solution into the cell causing it to swell or
break (lysis)
Hypertonic Solution
The water moves out of the cell into the
solution, causing the cell to shrink
Types of Solutions
Why doesn’t the plant cell undergo lysis?
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
Explain what is
happening in this
cartoon…
Facilitated Diffusion
Diffusion that is helped by proteins in
the membrane
Facillitated Diffusion
Diffusion vs. Facillitated Diffusion
MembraneMovements
Active
Active Transport
Pumps
Endocytosis Exyocytosis
Active TransportMovement of materials
from low concentration to high concentration using a
protein carrier that requires energy
(costs ATP)
Active T
ransportHigh Concentration
Low Concentration
What was ATP again???
Sodium-Potassium Pump
EndocytosisProcess of bringing
particles into a cell using extensions of the cellular
membrane
ExocytosisProcess of moving particles
out of a cell using extensions of the cellular
membrane (how wastes are excreted
from cells)
Endocytosis y Exocytosis
PhagocytosisThe process of
membrane folding that enables cells to bring “food” into the cell
PinocytosisThe process of
membrane folding that enables cells to bring “water” into the cell