H2O  Do you remember why we need cell division? For organisms to grow and to repair injuries. What do you think is necessary for cell division? Cells must be able to obtain energy and remove waste. How do you think cells gain their energy and remove waste? Through the cell membrane.

Demonstration – Woot woot!

For your viewing pleasure

Who wants to move around?

DIFFUSION & OSMOSIS

Methods of Cell Transport Substances move into and out of cells by several methods. One method of movement is diffusion.

Diffusion – write this down! Diffusion is the movement of particles (liquid or gas) from regions of higher density (concentration) to regions of lower density (concentration) So, this means from more crowded areas to less crowded areas. Cells DO NOT use energy for diffusion.

The Cell Membrane All cells, in all types of organisms, are surrounded by a cell membrane a thin layer of lipid and protein that separates the cell's contents from the world around it. functions like a gate, controlling what enters and leaves the cell. controls the ease with which substances pass into and out of the cell-some substances easily cross the membrane, while others cannot cross at all. selectively permeable

 Cells and Diffusion Water, carbon dioxide, and oxygen are among the few simple molecules that can cross the cell membrane by diffusion. Water moves through membranes by a type of diffusion known as osmosis. Diffusion is one principle method of movement of substances within cells, as well as the method for essential small molecules to cross the cell membrane.