Figure 1: (a) Development of colonies formed by laboratory strain of S. cerevisiae. Colonies develop on complex glycerol agar with Bromocresol purple, pH dye indicator with pKa of 6.3, the color of which changes from yellow at acidic pH to purple at more alkali pH. (b) Upper part: process of colony differentiation to cells with specific metabolic properties localized in upper (U cells) and lower (L cells) layers of the colony center, respectively. Viability: percentage of colony-forming cells is given. PCD: programmed cell death. Lower part: presence of subpopulations of dividing and nondividing cells.