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Question
Describe the role of CaCl2 in the preparation of competent cells?
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Solution
CaCl2 is known to increase the efficiency of DNA uptake to produce transformed bactrial cells. The divalent Ca+2 ions supposedly create transient pores on the bactrial cell wall by which the entry of foreign DNA is facilitated into the bactrial cells.
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RELATED QUESTIONS
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.
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.
Can you think and answer how a reporter enzyme can be used to monitor the transformation of host cells by foreign DNA in addition to a selectable marker?
Describe briefly the following:
Origin of replication
Write the role of ‘restriction sites’ in the cloning vector pBR322.
The genetic material of virus includes:
A suitable vector for gene cloning in higher organism is ______.
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.
Describe the role of Agrobacterium tumefaciens in transforming a plant cell.
Which of the following enzyme(s) are NOT essential for gene cloning?
- Restriction enzymes
- DNA ligase
- DNA mutase
- DNA recombinase
- DNA polymerase
Choose the correct answer from the options given below:
What is the basic biological nature of plasmids when used as cloning vectors?
Which of the following serves as an example of selectable markers commonly found in plasmid vectors like pBR322?
In blue–white screening, what do the white colonies indicate?
