Gene Regulation
Gene regulation. With pGLO, students analyze the growth of bacteria on various media and examine the roles that external and internal factors play in gene regulation. Gene expression in all organisms is carefully regulated to allow adaptation to differing conditions and to prevent wasteful production of proteins. The bacterial genes encoding the enzymes needed to metabolize the simple sugar arabinose are a perfect example. A promoter region upstream of these genes acts as molecular on/off switch that regulates their expression. The genes are activated only when arabinose is present in the environment. Bio-Rad's pGLO plasmid incorporates the arabinose promoter, but the genes involved in the breakdown of arabinose have been replaced with the jellyfish gene encoding GFP. When bacteria transformed with pGLO are grown in the presence of arabinose, the GFP gene switches on, causing the bacteria to express GFP and to fluoresce brilliant green. When students genetically re-engineer bacteria with the genes from a bioluminescent jellyfish they never forget the central mantra of molecular biology:
DNA ⇒ RNA ⇒ Protein ⇒ Trait — Green Fluorescence!
Transformed bacteria are grown on a petri dish.