Cells

Idea #6: All living organisms are made up of cells.

Every living thing is made up of cells. Some organisms have only one cell. We call them unicellular.

Other organisms (like us) are multicellular, with more than one cell. Humans have tens of trillions of cells. How many is that?

Ten trillion = 10,000,000,000,000

Now multiply that by anywhere from 5 to 10! That's how many cells a human body has!

Multicellular organisms don't have all their cells the same. Different cells in their bodies do different jobs. We have muscle cells, brain cells, bone cells, blood cells, all kinds of different cells, and each kind does its part in making us who we are.

But all cells are built very much alike, with the same basic parts. Before we start dividing all living organisms into their five kingdoms, we have to learn about the basic parts of cells.

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