Cell Transport

Selectively Permeable A property or characteristic of the cell membrane. It can allow some materials to pass through while keeping other materials out. Ex: allows water and nutrients in; wants to keep toxins out

Some things can pass through on their own, some need help, some cannot pass at all.

Diffusion The movement of molecules from a higher concentration (crowded) to a lower concentration (more space) http://www.biosci.ohiou.edu/introbioslab/Bios170/diffusion/Diffusion.html

Osmosis The diffusion of water through a cell membrane Happens when water enters the roots of a plant Water also moves from a higher concentration to a lower concentration How do you lower the concentration of water?

Osmosis Normal RBC RBC in pure distilled water

Equilibrium A state when the molecules are spread out evenly – but remember the molecules are still moving.

2 Types of Transport Across the Cell Membrane 1. Passive Transport The cell uses NO energy; the molecules don’t need any help to cross the cell membrane Diffusion Osmosis

2 Types of Transport Across the Cell Membrane 2. Active Transport The cell uses energy (from ATP) to move materials across the cell membrane a transport protein may escort the material Move from an area of low concentration to high concentration – against the normal direction of diffusion

Active Transport