9. Can you think and answer how a reporter enzyme can be used to monitor transformation of host cells by foreign DNA in addition to a selectable marker?
In recombinant DNA technology selection of transformed and non transformed cells can be done using reporter genes that encode for reporter enzymes. During the RDT experiment, the foreign gene is joined with a reporter gene. The reporter gene should be such that it produces a visible expression. For example, Lac Z gene which codes for enzyme beta-galactosidase is used as a reporter gene. The activity of this gene is not found in transformed cells as the product formed by its catalysation is not formed in transformed cells and bacterial colonies appear white. In non-transformed cells, this gene shows its activity and the catalysed product is formed, as a result of this, bacterial colonies appear blue. Thus, reporter enzyme can be used to monitor the transformation of host cells by foreign DNA in addition to a selectable marker.