Cell culture

This chapter provides the tools for using cell culture as an adjunct to the cell biology and molecular biology methods that break down the traditional borders between the disciplines of biology and virology. Cell culture allows looking at cells in their entirety from the outside before examining the intricacy of their component parts. Cells are counted in order to seed stock cultures with a known number of viable cells, to determine cell propagation rates, and to determine viability in a cell culture. Most vertebrate cell lines die after a finite number of divisions in cell culture, although rare immortal variant cells arise spontaneously in culture and can be maintained indefinitely as cell lines. DNA cloning and genetic engineering have given techniques that enable isolating specific genes, redesigning them, and inserting them back into cells. This technology has revolutionized the study of living cells. Eukaryotic cell lines are being developed with indefinite replication ability to express at least some of the differentiated properties of their cell of origin and to not necessarily cause tumors if injected into animals.