Permeases Phenotype

We labeled the lactose permease with a yellow fluorescent protein. The two specific phenotypes under discussion are first, above a certain threshold number of the permease, a cell has a fluorescent membrane and is capable of lactose metabolism second below this threshold, a cell is non-fluorescent and is incapable of lactose metabolism. The two phenotypes coexist in a population of cells (Fig. 22.7B) and show a bimodal distribution (Fig. 22.7C). This threshold is determined to be 300, corresponding to a big burst of permease production. 

---