Question
- Why are engineered vectors preferred?
- A vector is engineered with three features, which facilitate its cloning within the host cell. List the three features and explain each one of them.
✓
Answer
- Engineered vectors help easy linking of foreign DNA.
- They facilitate selection of recombinants from non-recombinants.
- Features of Cloning vectors:
-
Origin of Replication (Ori):
- This is the sequence of DNA from where replication starts.
- Any piece of alien/ foreign DNA linked to it is made to replicate within host cell; it also decides the copy number of the linked DNA.
-
Selectable marker: A marker is a gene, which helps in selecting the host cells, which are transformants/ recombinants from the non-recombinant ones, eg ampicillin and tetracycline resistant genes in E.coli
-
Cloning site: The vector should have a few, preferably one unique recognition site to link the foreign DNA, presence of a particular cloning/ recognition site enables the particular restriction enzyme to cut the vector DNA.
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