Movement of

Materials

The Cell Membrane

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

Active Transport

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