Cells

Robert Hooke first named cells when he built a simple microscope and observed thin sections of cork. This is what he saw. Cells are the units of life All cells come from pre-existing cells.
 * The Cell theory states that:**
 * 1) All Living organisms are made up of cells or the products of cells

> Plant cells usually contain chloroplasts - tiny organelles that contain chlorophyll, which allows plants to convert the sun's energy into glucose and carbohydrates. > Plant cells usually have a large vacuole, containing water and dissolved minerals. > > **Links to great Cell sites:** > Biology 4 Kids - Cells - [][|Cells Alive] - an interactive web site > Virtual microscope - red blood cell smear - [] > Close up of blood cells - [] > Cell Biology clip (You Tube) - [] > [|3D Cell Explorer] animations of cell processes. > [|The Virtual Electron Microscope] - a lesson plan from Discovery Education.
 * Plant cells and Animal cells differ in three ways:**
 * Plant cells have cell walls made of cellulose (structural carbohydrate)
 * **Cells vary in size**
 * The smallest are bacterial cells (about 3 microns) up to some plant cells of 100 microns.
 * In humans, red blood cells are very small, and some nerve cells are very long.
 * In humans, red blood cells are very small, and some nerve cells are very long.