Definition: States that all living things are composed of cells, cells are the basic unit of life, and cells come from pre-existing cells.
Example: Combined efforts of Hooke, Leeuwenhoek, Schleiden, Schwann, and Virchow
Term: Type term here

Explaination and

In biology, cell theory is the historic scientific theory. That living organisms are made up of cells, that they are the basic structural/organizational unit of all organisms, and that all cells come from pre-existing cells. Cells are the basic unit of structure in all organisms and also the basic unit of reproduction. The three tenets to the cell theory are as described below: All living organisms are composed of one or more cells. The cell is the basic unit of life.

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."