why do all cells in a body have to have a copy of the whole DNA?

Question

For example why does a skin cell has a copy of how to make blood cells if their only job is just to do skin cell things?

In: Biology

Answer 1

Your ancestors billions of years ago were single cells that only had two was of dividing. Each of the two cells either got a whole copy (normal division) or they each got half (used to make sex cells). When your later ancestors hundreds of millions of years ago started hanging around together as multicellular organisms, those two types were too deeply set to change and other work arounds were used instead where cells don’t express all their genes.