The colonies of recombinant bacteria appear white in contrast to blue colonies of non-recombinant bacteria because of: a.Non-recombinant bacteria containing beta-galactosidase b. Insertional inactivation of alpha-galactosidase in non-recombinant bacteria c.Insertional inactivation of alpha-galactosidase in recombinant bacteria d. Inactivation of glycosidase enzyme in recombinant bacteria plz explain the role of alpha galactosidase.bcz in ncert only beta galactosidase is given.?

Question

Answer

My answer is C option...and here is the explanation..alpha galactosidase is a glycoside hydrolase enzyme that hydrolyses the terminal alpha galactosyl from glycolipids and glycoproteins..it is encoded by GLA gene...and beta galactosidase is an exoglycosidase..which hydrolyses the beta glycosidic bond formed between a galactose and its organic hoiety...hope u clear??!!....

Answer

Role of Alpha-galactosidase

Alpha-galactosidase is an enzyme that plays a crucial role in carbohydrate metabolism. It is involved in the breakdown of complex carbohydrates, specifically the hydrolysis of alpha-galactosides. These include substances like raffinose and stachyose, which are found in many plants.

Hydrolysis of Alpha-galactosides
When alpha-galactosidase is active, it cleaves the alpha-galactosidic bond present in alpha-galactosides. This results in the release of galactose and a smaller carbohydrate molecule. The galactose can then be utilized by the bacteria as a carbon source, while the smaller carbohydrate molecule can be further broken down by other enzymes.

Insertional Inactivation of Alpha-galactosidase
In the case of recombinant bacteria, the alpha-galactosidase gene is often disrupted or inactivated by the insertion of a foreign DNA fragment. This insertion prevents the production of functional alpha-galactosidase enzyme.

Effect on Colony Color
As a result of the inactivation of alpha-galactosidase, the recombinant bacteria are unable to break down alpha-galactosides present in the growth medium. These alpha-galactosides are usually supplemented with a chromogenic compound called X-gal (5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside) in the growth medium.

In the presence of active beta-galactosidase, X-gal is hydrolyzed to produce a blue-colored compound. However, since the recombinant bacteria lack functional alpha-galactosidase, they are unable to break down X-gal. Consequently, there is no production of the blue compound, resulting in the colonies appearing white.

On the other hand, non-recombinant bacteria contain an active alpha-galactosidase enzyme. This enzyme can efficiently cleave alpha-galactosides and X-gal, leading to the production of the blue compound. Hence, the colonies of non-recombinant bacteria appear blue.

Conclusion
The role of alpha-galactosidase in this context is related to the hydrolysis of alpha-galactosides and the subsequent breakdown of X-gal, which results in the production of a blue compound. The absence of functional alpha-galactosidase in recombinant bacteria prevents the formation of the blue compound, causing the colonies to appear white.

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