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Question
Answer the following question.
β galactosidase enzyme is considered a better selectable marker. Justify the statement.
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Solution
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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RELATED QUESTIONS
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.
Plasmids are suitable vectors for gene cloning because these ______.
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.
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For selection of recombinants, insertional inactivation of antibiotic marker has been superceded by insertional inactivation of a marker gene coding for a chromogenic substrate.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.
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:
The following diagram showing restriction sites in E. coli cloning vector pBR322. Find the role of ‘X’ and ‘Y’ genes:
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?
Which of the following serves as an example of selectable markers commonly found in plasmid vectors like pBR322?
