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प्रश्न
A plasmid without a selectable marker was chosen as vector for cloning a gene. How does this affect the experiment?
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उत्तर
In a gene, cloning experiment, first a recombinant DNA molecule is constructed, where the gene of interest is ligated to the vector (the step would not be affected) and introduced inside the host cell (transformation). Since, not all the cells get transformed with the recombinant/plasmid DNA, in the absence of a selectable marker, it will be difficult to distinguish between transformants and non-transformants, because role of the selectable marker is in the selection of transformants.
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संबंधित प्रश्न
Name the selectable markers in the cloning vector pBR322. Mention the role they play.
Write the role of ‘restriction sites’ in the cloning vector pBR322.
Answer the following question.
Expand ‘YAC’ and mention what it was used for.
How does the β-galactosidase coding sequence act as a selectable marker? Why is it a preferred selectable marker to antibiotic resistance genes? Explain.
The genetic material of virus includes:
The colonies of recombinant bacteria appear white in contrast to blue colonies of non-recombinant bacteria because of ______.
Plasmids are suitable vectors for gene cloning because these ______.
Which of the following is not a genetic vector?
A cloning vector should possess which of the following characters?
- Origin of replication (Ori)
- Ability to destroy the alien DNA
- Cloning site to link the alien DNA
- The tumour inducing plasmid Ti.
- Selectable marker.
- Low molecular weight
The CORRECT combination 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?
Describe the role of CaCl2 in the preparation of competent cells?
Name the regions marked A, B and C.

For selection of recombinants, insertional inactivation of antibiotic marker has been superceded by insertional inactivation of a marker gene coding for a chromogenic substrate.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.
Describe the role of Agrobacterium tumefaciens in transforming a plant cell.
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.
The “Ti plasmid” of Agrobacterium tumefaciens stands for ______.
