This is a useful note I took in class:
Living things must maintain a high level of organized activity. Let's work backwards from the cell's point of view:
*The ultimate thing a cell must do is to produce copies of itself. All cells are mortal. Cell lines that do not reproduce will go extinct; therefore, logically, all existing cell lines must reproduce (simply because they are NOT extinct IF they are existing!).
*To reproduce, a cell must be able to pass information to its daughter cells, so that "they know what it knew". This information is passed in the form of genes made of DNA.
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