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प्रश्न
How does the β-galactosidase coding sequence act as a selectable marker? Why is it a preferred selectable marker to antibiotic resistance genes? Explain.
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उत्तर
Selective marker is used in the selection of recombinants on the basis of the ability to produce color in the presence of chromogenic substrate. β-galactosidase is an enzyme that converts galactose into lactose. In this, a recombinant DNA is inserted within the coding sequence of enzyme, β-galactosidase, which results in inactivation of an enzyme referred to as "insertional inactivation". As a result of this, non-recombinants will produce blue-colored colonies while the recombinants will produce color-less colonies.
The coding sequence for the enzyme β-galactosidase is preferred over antibiotic resistance genes because recombinants can be easily visualized and the process is less cumbersome.
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संबंधित प्रश्न
Draw a schematic sketch of pBR 322 plasmid and label the following in it:
(a) Any two restriction sites.
(b) Ori and rop genes.
(c) An antibiotic resistant gene.
Write the role of ‘restriction sites’ in the cloning vector pBR322.
Answer the following question.
β galactosidase enzyme is considered a better selectable marker. Justify the statement.
A clone is a ______.
A suitable vector for gene cloning in higher organism is ______.
Plasmid pBR322 has a PstI restriction enzyme site within gene ampR that confers ampicillin resistance. If this enzyme is used for inserting a gene for β-galactoside production and the recombinant plasmid is inserted in an E.coli strain.
What modification is done on the Ti plasmid of Agrobacterium tumefaciens to convert it into a cloning vector?
What is the basic biological nature of plasmids when used as cloning vectors?
Which of the following describes the function of a selectable marker in a cloning vector?
In blue–white screening, what do the white colonies indicate?
