Module 1 - Unit 2

 
Operon = a length of DNA, made up of structural genes and control sites
Structural genes:
Z transcribes mRNA and mRNA then translates B-galactosidase (hydrolyises lactose to glucose and galactose.)
Y transcribes mRNA and mRNA translates Lactose permease (transports lactose into the cell.)
Control sites:
Operator region, O = it can switch the structural genes on and off, so it essentially codes for the lac enzymes. 
Promoter region, P = binds to RNA polymerase to begin the transcription of the structural genes Z and Y. 
Regulatory gene, I = It is not part of the operon. Codes for the mRNA molecule for the repressor protein, which has binding sites for Lactose and the operator site. The repressor protein binds to the operator site.