How do molecules move around? Diffusion is the movement of molecules from a HIGH concentration to a low concentration

Whaddaya mean, molecules MOVE ????? You gotta be kidding me! Yeah, right diffusion animation

OSMOSIS WATER through a membrane Osmosis is the movement of from a high to a low concentration through a membrane

To go into or out of a cell by diffusion or osmosis (without using energy) A molecule must be . . . The right size to pass through an opening The right shape to pass through an opening Going from a high to a low concentration

Cell membranes must have Small openings for small molecules Medium openings for medium molecules And the BIG stuff is a whole other story!!

SMALL openings in between phospholipids for small molecules: Examples: Water Oxygen Carbon dioxide Alcohol

Medium Protein Doorways for medium sized molecules Examples: Glucose Amino Acids Some Lipids Some Starches

Passive Transport Materials moving into or out of the cell without using any energy Examples: Diffusion Osmosis Open protein doorways (channels)

Active Transport Needed for molecules going from a low to high concentration (reverse diffusion) Needed for LARGE molecules Active = uses up ENERGY (ATP)

Active transport from a low to a high concentration – ENERGY

The BIG stuff Endocytosis Exocytosis Membrane surrounds particle to form a vesicle which then moves INTO the cell Exocytosis Vesicle surrounds particle and moves to membrane and OUT of the cell

The cell membrane is “selectively permeable”. = It controls what enters and leaves the cell.

The Cell Membrane PLUS