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MODEL PAPER 5 — BIOLOGY STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceBIOLOGYMODEL PAPER 54 Marks
Question
Answer the following questions with respect to recombinant DNA technology:
i. Why is plasmid considered to be an important tool in rDNA technology? From where can plasmids be isolated? (Any two sources)
ii. Explain the role of ori and selectable marker in a cloning vector.
iii. r-DNA technology cannot proceed without restriction endonuclease. Justify.
✓

Answer

i. Plasmid considered to be an important tool in rDNA technology as it can act as vector/can self-replicate to form multiple copies/have selectable markers/ small in size will facilitate insertion/presence of 'Ori'- E. coli, Agrobacterium tumefaciens, Salmonella typhi, Bacteria.
ii. Role of 'Ori'- this is a sequence from where replication starts/any piece of DNA when linked to this sequence can be made to replicate with in the host cells/controls copy number of linked DNA.
Role of selectable marker helps in identifying and eliminating non-transformants, and selectively permitting the growth of transformants during recombinant DNA technology.
iii. Restriction endonuclease identifies a specific palindromic sequence of DNA and cut the DNA at the specific sites in both the host as well in desired/foreign DNA, thereby creates "sticky ends" facilitating ligation to form a recombinant DNA.

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