Chapter 2 Lesson 3Moving Cellular Materials

Cell MembraneThe cell membrane is selectively

permeable◦It allows certain things into the cell

while keeping others out◦Another term is semi- permeable◦The chemical properties and physical

properties determine if it can enter the cell Physical- the size of the particle

Passive TransportThe movement of substances

into or out of the cell without using energy◦Small molecules- like Carbon dioxide

or◦Oxygen◦Depends on the amount of the

substance on each side of the membrane

Passive TransportDiffusionOsmosisFacilitated Diffusion

DiffusionThe movement of a substance

from a higher concentration to a lower concentration

Diffusion will continue until equilibrium- equal amounts of the substance on both sides of the membrane

OsmosisSpecial kind of diffusionDiffusion of water through a semi-permeable

membraneOsmosis continues until equilibrium is

reachedSolute- the material dissolved ( sugar)Solvent- the solution or liquid (water)

Facilitated DiffusionSome molecules are too large or

chemically unable to pass through the membrane

Some molecules move with special helper proteins called transport proteins

2 types of proteins◦Carrier- carry things like glucose or sugar

molecules◦Channel- carry things like sodium or

potassium ions

Facilitated Diffusion

Active TransportMovement of substances through

a cell membrane using energyGoes against the concentration

gradientLow concentration to high

concentration

Endocytosis and ExocytosisSome substances need to enter

the cell but they are too large to do so.

Endocytosis- To enter the cell- the cell surrounds the

substance with a membrane

Exocytosis- A cells vesicle release their contents

outside the cell

Endocytosis

Exocytosis