Saturday, May 25, 2013

Types of plasmid!

I learnt genetic engineering, and of course, about plasmids. But, when I was questioned about the types of plasmid, God, I was blinking! :(

I had known plasmid only as a vector most times, I was aware of the types of vectors but, types of plasmids? :(

Okay, It's not a great shame, I learnt it now! Let me share here about the types of plasmids, just what I learnt.

Based on the functions of a plasmid they are classified as,

Resistance Plasmids:
These are the plasmids which have resistance genes. For example the gene coding beta lactamase which offers resistance against beta lactum antibodies like ampicillin. This is an important thing which is used while performing cloning experiments for checking the transformation. This was called as "R Factor" before the discovery of plasmids.

Fertility plasmids (F Plasmids):
And, these type of plasmids they have important genes called tra genes, never wonder, tra genes are transfer genes which are essential for the non sexual transfer in bacteria. This helps in formation of Pili and conjugation as a result.

Col plasmids:
These plasmids are the ones which have special genes for inhibiting the growth of similar bacterial strains i.e., bacteriocins.

Degenerative plasmids:
These are things which contains special genes responsible for digesting toulene like things. For example, I could say "Super bugs" they have engineered plasmid containing genes for digesting several types of chemicals and it is used for clearing oilspills.

Virulence plasmids:
These are the ones which makes us to hate bacteria. Yes, these make the bacteria virulent i.e., disease causing. You hate it, right?

Still I have one more thing to explain, "Promiscuous plasmid". This was asked in my university exam and adding to the sadder part, I didn't know the answer. But, nothing to worry, I got the answer now.

Promiscuous plasmids: These are plasmids which are self transmissible to a wide variety of organisms. They allow transfer of DNA to other species.

You know any other types of plasmids? Then share with me in the comment section, anything was not clear? comment then.

Take care. Bye :) :)


  1. Added to my knowledge TY. I hope I will never forget. I hate biology but love photographing nature, flowers and butterflies. :-)

    1. :) I love butterflies and also Biology!

  2. Hi..nice post! We love plasmids too and we love posts about plasmids.

    Joanne (Exec Dir of Addgene, "a better way to share plasmids")