SAS' Cell Biology Page

Cell Theory

Cell Theory states that cells are the basic unit of all living things, cells are the basic functional and structural unit of all living things, and cells are always made from preexisting cells. By studying and examining cells, we gain an understanding for how our bodies, and the bodies of other organisms work.

It is this basic understanding that leads to one of the fundamental requirements for life. The smallest living organisms are made of a single cell, whether they are prokaryotes (bacteria), or single-celled eukaryotes (e.g. protista). When we examine how multicellular organisms function, such as ourselves, we come back to how muscles cells contract, nerve cells communicate, white blood cells detect and eliminate infections. When we look at the structures of the bodies of organisms, when start at the building blocks, the cells. The shape of a bone starts with the shape of bone cells. The shape of our brain starts with how the brain's nerve cells connect with each other. Cell Theory is the most basic condition for determining if something is alive.