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

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!! Oxygen Carbon dioxide Water Glucose

Examples: Water Oxygen Carbon dioxide Alcohol Method of Movement: Diffusion SMALL openings in between phospholipids for small molecules: Examples: Water Oxygen Carbon dioxide Alcohol

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

Method of Movement: Passive Transport Open ‘protein doorways’ for medium sized molecules Examples: Glucose Amino Acids Some Lipids Some Starches

Method of Movement: Passive Transport Materials moving into or out of the cell without using any energy Examples: Diffusion Osmosis Open protein doorways (channels) *from a high to a low concentration

Method of Movement: Active Transport Closed ‘Protein Doorway’ for LARGE molecules Needed for molecules going from a low to high concentration (reverse diffusion) Active = uses up ENERGY (ATP)

Active transport from a low to high concentration – ENERGY

Passive Transport: Open protein doorway Diffusion Passive Transport: Open protein doorway Active Transport: Locked protein doorway

The Method of Movement: Endocytosis and Exocytosis The BIG 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 “The Fluid Mosaic Model”