Research involving cells is often accomplished by removing the cells from an individual and growing them in a sterile dish with the nutrients required for their survival. Growing cells for research use is termed “cell culture”. Just by watching normal cells in cell culture it is obvious that their division is regulated by something. Normal cells in culture grow until the bottom of their dish is carpeted with the cell. The layer is only 1 cell thick. Once this density is reached, they stop dividing because there is no more space. If one cell dies, an adjacent one will divide to fill in the space. Additionally, normal cells will divide a certain number of times after which time, the division process halts. There are a certain pre-determined number of generations that may be produced and then there is no more dividing. Eventually, the entire culture will die.
A second major difference between normal cells and
Differentiation is the term given to describe the specialized function a given cell has. Differentiation and proliferation are closely tied together. In general, a cell that proliferates at a high rate loses some of its specialized function. The problem is, it really doesn’t have time to perform a specific function since its too busy dividing. Cells that perform a highly specific function (i.e. differentiated) have a lower rate of proliferation. Researchers are studying the possibility of making