Question

Why is it important for vectors to have their own Ori?

          a.) It isn’t, they are attached to the chromosomal DNA and will divide from its Ori

          b.) The Ori will protect the vector from the organism’s restriction enzymes

          c.) The Ori is what allows us to select for those cells that actually transformed

          d.) It has to be able to replicate independently of the chromosomal DNA

Answer 1

Option D

Ori is origin of replication. It is a sequence on both linear chromosome and plasmid chromosome because of which both linear and plasma chromosomes can replicate independently of each other. If this sequence is absent, then the chromosome will not be able to replicate and therefore cannot be maintained inside a cell. This sequence is a characteristic feature of both prokaryotes and eukaryotes.

First option is incorrect because if origin of replication is absent in plasmid, then the plasmid will be ultimately lost. It will not use origin of replication from linear chromosome.

Second option is incorrect because it is not associated with the protection of organism from restriction enzymes. In fact, if a suitable restriction enzyme is used, then this site can be digested.

Third option is incorrect because it does not help us to select which organisms have been transformed. This is the function of selectable marker.

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