What would the most likely phenotype of an E coli colony con

What would the most likely phenotype of an E. coli colony containing pUC18 (without an insert fragment) be if the following de novo mutations occurred early in the growth of a single cell into a colony on your plate (assuming plate contains X-gal, IPTG and Amp)? a. A frameshift mutation in the fifth codon lacZ gene in pUC18. b. A loss of the pUC18 plasmid. c. A deletion of bps at positions 19-25 of the ampicillin resistance gene open reading frame.

Solution

A. a frameshift mutation will produce a non functional lac z gene which cannot produce the dsired enzyme to grow in the plates containing X-gal. so there will be no colony will be seen which have the mutation.

B. if there were loss of pUC18 plasmid then there will be no growth in the given media because the media contains Amp and the Amp resistance gene is on the pUC18 plasmid.

C. if there were deletion in the Amp gene that will make the gene inactive non functioal and that will lead to loss of Amp esistance. As the media containd Amp thats why no colony will be seen.