A cell culture maintains cells outside their original organism under suitable conditions. Cells require an appropriate nutrient supply, water, temperature, pH and waste removal. Oxygen requirements depend on the cell and its metabolism. Different cells need different media and signals; one culture condition does not suit every species or tissue. Contamination can introduce competing cells or microorganisms and alter the observed population.
Cultures support applications including yeast production, plant propagation, protein manufacture and some tissue replacement methods. Cell counts, viability percentages and growth curves describe different properties: a large total count can include dead cells. During ideal exponential growth, N=N0×2ᵍ, where g is the number of doublings. Real cultures eventually slow as resources, space or waste conditions change.
Example 1
A culture begins with 500 cells and completes three ideal doublings. Find its count.
500×23=4000 cells. This assumes no death and sufficient resources throughout.
Example 2
A sample has 200 counted cells, of which 170 are viable. Find viability.
Viability =200170×100=85%. The remaining 15% are counted but not viable.
Watch out: Nutrient, signal and environmental requirements differ among cell types.