Question

For the antibody test scientists needed to make a lot of coronavirus proteins. They cloned the coronavirus spike protein gene in a plasmid. The plasmid was transformed into E. coli. The E. coli must be grown to a high cell count in liquid media before the protein can be made. Propose how the scientists can turn on a gene at a specific time.

Answer 1

The scientists can turn on the expression of a recombinant gene in a plasmid by placing the gene of interest(the spike protein gene) under the control of a known simple promoter -operator control of E.coli.The most simple gene expression control and widely used is Lac promoter and operator of lac operon,along with the lac repressor coding gene.For turning the gene of interest on,the E.coli bacteria must be grown solely in the prescence of lactose,which will turn on the promoter and operator by inactivating the lac repressor,and the gene expression will be switched on .But there must not be any Glucose in the medium otherwise the expresssion will be stopped untill the whole glucose is utilized first due to catabolite repression wich involves the inhibition of CAP -cAMP complex formation required for gene expression and no protein will form from the desired gene.