Getting In and Out of Cells Cellular Transport Getting In and Out of Cells

Introduction Homeostasis--keeping the proper conditions inside, regardless of the conditions outside Example: We keep the inside of our bodies not too hot and not too cold, but “ Just Right.” The cell membrane controls what goes in and what goes out of each cell.

Movement through a cell membrane depends on three things: 1. the size of the molecule 2. the path that the molecule takes (slipping through the lipid fence or going through a protein “gate”) 3. whether or not energy is used

Passive Transport Passive Transport: Movement of substances through the cell membrane without the input of energy YOU DON’T NEED THIS ATP

Equilibrium is reached. Diffusion 1. Diffusion: Molecules move from an area of high concentration (lots of molecules) to an area of low concentration (few molecules) until they spread out evenly: Equilibrium is reached. http://www.biosci.ohiou.edu/introbioslab/Bios170/diffusion/Diffusion.html

Example Perfume in a room Food coloring in water Oxygen diffuses from lungs into red blood cells

Osmosis 2. Osmosis: The diffusion of WATER across a selectively permeable membrane http://www.stephsnature.com/lifescience/osmosisanimations.htm

Selectively Permeable Membrane allows some things to pass through, blocks others

Example Water moving in and out of animal cells and plant cells http://www.youtube.com/watch?v=_slUL3kMZlU&feature=related

Facilitated diffusion 3. Facilitated diffusion: Large molecules diffuse with the help of transport proteins (larger openings in the cell membrane: the gate) http://www.d.umn.edu/~sdowning/Membranes/diffusionanimation.html

Example Glucose moving into a cell through the transport protein “gate”