The relationship between molecular size and electrphoretic mobility in agarose gels as determined from a single population of growing RNA molecules.

Growing RNA molecules obtained from a defined transcription unit, the 75 S RNA transcription unit in Balbiani ring 2 of Chironomus tentans, have been analysed by electrophoresis in agarose. This set of RNA molecules forms a broad distribution of molecules with sizes ranging from very small up to the final product of giant size corresponding to 75 S RNA. The relative molecular weights along the migration path were calculated from a simple activity relationship derived from the expected distribution properties of a single population of growing RNA molecules. It was concluded that there is a linear relationship between the molecular weight and the logarithm for the mobility.