CoachCell culture keeps cells alive and dividing outside the organism, in a sterile medium supplying nutrients, salts, growth factors and, for animal cells, a surface to attach to, at the organism’s temperature. Bacteria and yeasts grow in simple media and double in minutes to hours; animal cells taken from a tissue (primary cultures) divide a limited number of times, while cell lines derived from tumours or transformed cells divide indefinitely. Culture makes the cell an experimental object: one type, one medium, one variable at a time.
Examples
Example 5.15 (A growth curve)
A flask of E. coli in a rich medium at : a lag of half an hour, then exponential growth — the count doubles every , so — until a nutrient runs out or wastes accumulate and the culture reaches a plateau near cells per millilitre. From a single cell, cells in ten hours. The same curve, with a doubling time of a day, describes a culture of human cells.