Final Answer:
The colonies will appear blue.
Step-by-step explanation:
The lacZ gene encodes for β-galactosidase, an enzyme that catalyzes the hydrolysis of lactose into glucose and galactose. The introduction of the MCS (Multiple Cloning Site) into the lacZ' gene disrupts the normal functioning of β-galactosidase. As a result, when X-gal (5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside) is present in the medium, the colonies carrying the disrupted lacZ' gene will produce a blue color.
The blue coloration arises from the cleavage of X-gal by residual β-galactosidase fragments within the lacZ' gene. In the absence of a functional lacZ' gene, the enzyme is unable to fully process X-gal, leading to the accumulation of a blue product.
This colorimetric assay is widely used in molecular biology to identify transformed bacterial colonies carrying recombinant plasmids. The blue coloration simplifies the screening process, allowing researchers to visually distinguish between colonies with and without the desired insert.
The choice of blue color for transformed colonies is advantageous as it provides a quick and straightforward method for identifying successful transformations. This visual screening method is time-efficient and facilitates the rapid identification of positive clones in genetic engineering experiments, streamlining the research process.