Question

The colonies of recombinant bacteria appear white in contrast to blue colonies of non-recombinant bacteria because of
A. Non-recombinant bacteria containing β - galactosidase
B. Insertional inactivation of α - galactosidase in non-recombinant bacteria
C. Insertional inactivation of α - galactosidase in recombinant bacteria
D. Inactivation of galactose enzyme in recombinant bacteria.

Answer 1

Alpha-galactosidase is a glycoside hydrolase enzyme that then catalyzes the hydrolysis of glycolipids and glycoproteins from its terminal alpha-galactosyl moieties. An insertional inactivation is an approach used to classify transformed bacterial cells that have taken recombinant plasmids in bacterial DNA technology.

Complete answer:
A genetically engineered plasmid classified by unique qualities is pUC18. The vector contains the Ampicillin resistance gene and the bacterial lacZ gene insert. Inside the lacZ gene, a polylinker site with a number of restriction-enzyme sequences is located. An enzyme called β-galactosidase which breaks down a chromogenic substrate called X-gal is the output of a functional lacZ gene. Thus, the substrate is degraded when bacterial cells carrying pUC18 plasmids are grown on an agar-based medium with X-gal added. The pUC18 plasmid-containing bacterial cells that give rise to blue colonies. The incorporation into the polylinker site of a fragment of foreign DNA leads to disruption to the lacZ gene which is no longer functional (insertional inactivation). It is useful to characterize recombinant pUC18 plasmids by using LacZ alpha-gene as a selectable marker. This is performed on an agar-based medium containing X-gal by cultivating bacterial cells containing the recombinant plasmid. The disrupted lacZ gene is not expressed, which indicates that it does not code for β-galactosidase production. X-gal doesn't really continuously break down the bacterial cells with the recombinant plasmid, and that these give rise to white colonies.

So, the correct answer is option C.

Additional Information:
The glycoproteins and glycolipids which have the same basic sequence with terminal sugars alpha-1-2-linked fucose linked to the penultimate galactose are coated with red blood cell (RBC) layers. This molecule of galactose is labeled as the antigen of H. Types A, B, AB, and O of the blood differentiate only in sugar associated with the penultimate galactose. For type B blood, this associated sugar is an alpha-1-3-linked galactose. For type B blood, this associated sugar is an alpha-1-3-linked galactose. This terminal galactose molecule can be separated using alp-GAL, converting RBC to form O.

Note: Alpha galactosidase from Aspergillus niger (a common mould) is an active ingredient in products marketed to limit the production of stomach gas after having gas-causing foods. At 55 degrees C, it is optimally active, where after its half-life is 120 minutes. Agalsidase alpha and agalsidase beta are defined as two recombinant forms of human Alpha-galactosidase.