Cloning vectors are the DNA molecules that can carry a foreign DNA segment into the the host cell.The vectors used in recombinant DNA technology can be plasmids, cosmids, bacteriophages etc.
  • Plasmids: Self replicating, circular,  extra chromosomal DNA present in bacteria. Plasmids have only one or two copies per cell.
  • Bacteriophages: Virus infecting bacteria. Bacteriophages have high number per cell, so their copy number  is also high in genome.
  • Cosmids: Hybrid vectors derived from plasmids which contain cos site of lambda phage.
Feature required to facilitate cloning into vector: Origin of replication, Selectable marker, unique restriction sites.
The purpose of cloning vector is often to make numerous copies of the inserted gene.
Expression Vectors: The cloning vector containing suitable expression signals to have maximum gene expression, is called expression vector.
The following expression signals are introduced into gene cloned vectors to get maximum expression:
  • Insertion of a strong promoter.
  • Insertion of a strong termination codon.
  • Adjustment of distance between promoter and cloned gene.
  • Insertion of transcription termination sequence.
  • Insertion of a strong translation initiation sequence. pCI mammalian expression vector 
Example: An expression vector pSOMI containing promoter operator (PO) for production of a chain of somatostatin (somI).
Expression vector are designed for the expression of protein product coded by that inserted gene.

12 Comments

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  1. this information is much more easy to understand remembering

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  2. this information is much more easy to understand remembering

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  3. Really good . but notify more example of expression vectors

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  4. amazing site. happy

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  5. So if there is a gene of interest for which one wants to produce a recombinant protein, how are the two types of vectors related or used? Does one first identify the gene, insert it into a cloning vector, amplify it and then transfer it into a prokaryotic cell for expressing the protein? Explanation of the steps generally followed to achieve this would be appreciated.

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  6. Montasir Al-mansi25 February 2018 at 01:17

    very good information, but why not allow to copy this information ?

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