BIOL 1500 Lecture Notes - Lecture 1: Lac Operon, Operon, Repressor
Document Summary
A : no , cell only trascribes certain genes at certain time. A : mostly its energy cost , cells save energy by only producing proteins they need , gene control also allow for di erentiation of cell types in multicellular organism. Genes in prokaryotes are organized into operons , groups of genes that are always transcribed together the lac operon = lactose digesting enzymes. Prokaryotes dont have histon , so their promoters are alwyas on. When lactose is not present we dont need lactose digestiong enzyme a repressor proteins block transcription. But when lactose is present transcritption of the operon can occur. Lactose activates the repressor , repressor bind to lactose changing shape and releasing the operator. 3 types of bacterial : one never transcribes one always and one in the middle. > this one with regulation can have advatages in both environment with or without lactose.
