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प्रश्न
Answer the following question.
β galactosidase enzyme is considered a better selectable marker. Justify the statement.
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उत्तर
The selective marker is used in the selection of recombinants on the basis of the ability to produce colour in the presence of a 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".
The coding sequence for the enzyme β-galactosidase is preferred over antibiotic resistance genes because recombinants can be easily visualized.
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संबंधित प्रश्न
Name the selectable markers in the cloning vector pBR322. Mention the role they play.
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.
Describe briefly the following:
Origin of replication
Write the role of ‘restriction sites’ in the cloning vector pBR322.
How does the β-galactosidase coding sequence act as a selectable marker? Why is it a preferred selectable marker to antibiotic resistance genes? Explain.
Which of the following statement is not true for a clone?
Which of the following is not a cloning vector?
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.
A plasmid without a selectable marker was chosen as vector for cloning a gene. How does this affect the experiment?
The figure below shows the structure of a plasmid.
A foreign DNA was ligated at BamH1. The transformants were then grown in a medium containing antibiotics tetracycline and ampicillin.
Choose the correct observation for the growth of bacterial colonies from the given table.
