Notes # ______
Date _________
METHODS OF TRANSPORT: HOW MATERIALS CROSS THE CELL MEMBRANE
CELL
Section 3.4 Passive Transport: Diffusion, Facilitated Diffusion and Osmosis
Key Concept: Some molecules move on their own into or out of cells because of
concentration differences on opposite sides of the membrane without the cell
using energy. This is called Passive Transport.
Methods of Passive Transport - _________________________________
1. _____________ – Net (overall) movement of molecules from area of higher
concentration to an area of lower concentration
Ex._______________________________________________________
2. _______________________ – Movement of material through the cell
membrane by a “helper” transport protein (channel or carrier) that binds
specifically to the molecule
3. _____________ – Diffusion of water molecules through a membrane from an
area of higher water concentration to one of lower water concentration.
Super Important Factoid:
Higher water concentration in solution corresponds to lower solute concentration
Lower water concentration in solution corresponds to higher solute concentration
Comparing Solutions:
Isotonic – compared solution has the same solute and water concentrations
Hypertonic – compared solution has a Higher solute concentration (less water)
Hypotonic – compared solution has a Lower solute concentration (more water)
Notes # ______
Date _________
Section 3.5 Active Transport: Membrane Pumps, Endocytosis and Exocytosis
Key Concept:Cells use energy to transport materials across the cell membrane.
Methods of Active Transport - ______________________
1. _____________________________
*Moves molecules across membrane from low to high concentration areas
*Involves a transport molecule that spans the cell membrane
*Transport molecule binds to 1 or 2 specific target molecules
*Binding causes the transport molecule to change shape and move the molecules
*The ATP (adenosine triphosphate) molecule transfers E to the transport
protein molecule giving it the E it needs to do to move molecules through the
cell membrane.
2. ________________ - Taking in of materials by engulfing them in a vesicle

_____________ – Cell membrane engulfs large particles or whole organisms

ex. White blood cell engulf a bacteria, Amoeba engulfs paramecium
__________________ – Cell membrane engulfs liquid droplets

__________________ - Special receptors that are embedded in a coated
pit of the cell membrane are used to attract and transport materials into
the cell.
3. ___________ – Release of substances from cell by fusing vesicle with
membrane
ex. Secretory vesicles. Unicellular organism excreting waste.