Abstract
HeLa cells have been grown at different rates in steady-state continuous and semicontinuous culture. Slowly growing cells contain more protein and less RNA than rapidly growing cells, but appear to synthesize protein by less efficient use of the available RNA. The rate of RNA accumulation increases rapidly with increasing growth rate and rapidly growing cells contain more ribosomal subunits, and more and larger polysomes, but have fewer monoribosomes than slowly growing cells.