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Question
Name the selectable markers in the cloning vector pBR322. Mention the role they play.
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Solution 1
In the cloning vector pBR322, ampicillin and tetracycline resistance genes serve as selectable markers. They help in the selection of transformed cells from nontransformed cells. They also help distinguish recombinant cells from nonrecombinant cells.
Solution 2
The selectable markers in the cloning vector pBR322 are the genes encoding resistance to antibiotics, specifically ampicillin and tetracycline. These markers play a crucial role in identifying and selecting transformants. When a foreign DNA is inserted into the vector, it disrupts one of the antibiotic resistance genes, often the tetracycline resistance gene. This results in transformants that are resistant to ampicillin but sensitive to tetracycline, allowing selection of recombinant cells. The markers enable growth of only those bacteria that have taken up the plasmid and help distinguish recombinants from non-recombinants through antibiotic sensitivity patterns.
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.
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?
Answer the following question.
β galactosidase enzyme is considered a better selectable marker. Justify the statement.
A clone is a ______.
Which of the following statement is not true for a clone?
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
Which of the following is not a cloning vector?
What does ‘competent’ refer to in competent cells used in transformation experiments?
What modification is done on the Ti plasmid of Agrobacterium tumefaciens to convert it into a cloning vector?
