Cells are the smallest parts of living organisms. There are many types of cells, and all cells do special jobs. All cells work together to keep the organism healthy.

Skin cells help protect the insides of our bodies. Muscle cells help us move. A plant's root cells help it drink water.

You have to use a microscope to see most cells. The first cells were seen with a microscope in 1665. It was a long time before scientists realized that all plants and animals are made up of cells.

Cells have important things inside them. All of these things help the cell do its job.

Graphic by Elycia

Click HERE to visit BrainPop and see a cool video about cells. Be sure to click your back button and come back when you're finished!

Did you know that you have seen a cell? There is one you can see without a microscope! Can you guess what it is? It's an egg!

Any egg is a single cell. Chicken eggs, ostrich eggs, even alligator eggs are all cells. Have you noticed the different parts inside an egg? Those parts have special names.

Cells are always dying and new ones are growing. Your body doesn't have a lot of the cells it had last week. It has new ones now! Your body has about 75 trillion cells.

There are two different types of cells. One type is called prokaryotic. These cells do not have a nucleus or other organelles with membranes around them. Bacteria is a prokaryotic cell.

The other type of cell is called eukaryotic. These cells have nuclei. The organelles in them usually have cell membranes, too. Plant and animal cells are eukaryotic cells.

Photograph by Lori Miller

Science Fun:  See if your school has a microscope. Ask your teacher to help you look at some objects under the microscope. Look at a feather. Look at a splinter of wood. Look at a piece of onion skin. See if you can see some individual cells in the objects you look at. It is very easy to see cells in onion skin if you put a tiny drop of food coloring on the onion skin. Try it, but be sure to have an adult's help!