The microorganism used in this laboratory was E.coli, which is a prokaryote. In general, prokaryotes are small, compact genomes that have a single round DNA molecule. The genes are packed very tightly, 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: introns are absent, so not all genes are 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 necessary for the transport and metabolism of lactose. An operon is made up of three characteristics: promoter, operator and structural genes. The promoter site is where the 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 structural genes, which are numerous genes, which encode the enzymes of a metabolic pathway, transcribing as a whole. There are two techniques : ...