PERMEABILITY OF MEMBRANES

Permeable – substance is able to cross a membrane

Impermeable – substance cannot pass across the membrane

Selectively permeable – some substances can pass and some cannot pass

CELL TRANSPORT• Passive Transport – no energy

• Diffusion• Facilitated diffusion• Osmosis

• Active Transport – energy required• Endocytosis• Phagocystosis• Exocytosis

PASSIVE TRANSPORT Passive Transport Clip Summary:

Diffusion – movement of ions from area of high concentration to an area of low concentration

Facilitated – aided movement across the cell membrane using protein channels

PASSIVE TRANSPORT (CONTINUED)

Osmosis – facilitate diffusion of WATER using aquaporins (water channel proteins) Since the cell membrane (lipid bilayer) has a

hydrophobic layer, it does not allow water molecule to pass through freely

ACTIVE TRANSPORT

Introduction Active Transport Clips

Endocytosis and Exocytosis Phagocytosis

ACTIVE TRANSPORT SUMMARY

Movement of materials from an area of low concentration to an area of high concentration – requires energy

Protein pumps – small molecules, use ATP, change shape, bind substance on one side and release on the other side of the membrane

Endocytosis – cell membrane creates a vesicle that contains the particle

Exocytosis- vesicle fuses with cell membrane and releases particle out of the cell