It’s sending electrical impulses, pumping blood, filtering urine, digesting food, making protein, storing fat, and that’s just the stuff you’re not thinking about! You can do all this because you are made of cells — tiny units of life that are like specialized factories, full of machinery designed to accomplish the business of life. Cells make up every living thing, from blue whales to the archaebacteria that live inside volcanos. Just like the organisms they make up, cells can come in all shapes and sizes.
