Question

Explain the features of cloning vectors.

Answer 1

The plasmids are the small extra-chromosomal DNA present in the bacteria which are commonly used as a cloning vector. The desired gene fragment can be inserted in the plasmid and then introduced into the host. The plasmid is selected on the basis of certain features.

• The plasmid can be isolated from the bacterial cells very easily.
  
• There should be single restriction sites for the restriction enzyme. This would allow proper integration of the gene without disintegration of the plasmid.
  
• The molecular weight of the plasmid should be high which would allow easy separation of the plasmid from the cellular debris.
  
• The copy number of the plasmid should be high in order to obtain huge amount of products from the gene.
  
• The plasmids and the bacteriophage DNA have the ori site. This is the site which helps in the initiation of replication.