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प्रश्न
Explain the importance of ‘Selectable marker’, with the help of a suitable example.
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उत्तर
Importance of Selectable Marker:-
(i) It helps in identifying and eliminating non-transformants.
(ii) It selectively permitting the growth of the transformant.
e.g- The genes encoding resistance to antibiotics such as Ampicillin, Chloramphenicol Tetracyclin or Kanamycin are considered useful selectable markers for E.coli because normally E-coli does not carry resistance against any of these antibiotics.
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संबंधित प्रश्न
Name the selectable markers in the cloning vector pBR322. Mention the role they play.
State how has Agrobacterium tumifaciens been made a useful cloning vector to transfer DNA to plant cells.
Why is the coding sequence of an enzyme β-galactosidase a preferred selectable marker in comparison to the ones named above?
Answer the following question.
β galactosidase enzyme is considered a better selectable marker. Justify the statement.
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 is correctly matched?
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?
For selection of recombinants, insertional inactivation of antibiotic marker has been superceded by insertional inactivation of a marker gene coding for a chromogenic substrate. Give reasons.
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.
