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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.
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
Why is the coding sequence of an enzyme β-galactosidase a preferred selectable marker in comparison to the ones named above?
Which of the following is not a genetic vector?
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For selection of recombinants, insertional inactivation of antibiotic marker has been superceded by insertional inactivation of a marker gene coding for a chromogenic substrate.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 following diagram showing restriction sites in E. coli cloning vector pBR322. Find the role of ‘X’ and ‘Y’ genes:
