The microorganism used in this lab was E.coli, which is a prokaryote. In general, prokaryotes are small, compact genomes that have a single, round DNA molecule. The genes are tightly packed, with almost no space between them. In the case of E.coli it has thrA, 1 nucleotide, thrB, thr C. The enzymes of a single biochemical pathway are encoded by the operon: the introns are absent, so all the genes are not interrupted and the sequence is not repetitive . An operon is a group of adjacent genes that are transcribed as a unit into a single polycistronic mRNA molecule. The lac operon is required for lactose transport and metabolism. An operon consists of three features: promoter, operator, and structural genes. The promoter site is where RNA polymerase (Plac) is attached. The operator is the site where the repressor protein binds, blocking the binding of RNA polymerase, which in turn stops transcription of the operon. Finally there are the structural genes, which are numerous genes, which code for the enzymes of a metabolic pathway, transcribing them as a unit. There are two techniques ...