Alan KAY kay at
Mon Feb 24 11:39:03 EST 1997

In article <5ep0p4$gs at>, e.hillery at says...
>Rani Geha wrote:
>"what is the difference between transfection and transformation?"
>Well, as far as I can tell, just a matter of semantics really.  However,
>saying that, transfection is usually used when you are introducing foreign
>DNA (usually in plasmid form) into cells where you would then assay for its
>activity, like in the case of "reporter genes".  Transformation is generally
>used when you introduce that plasmid into a bacteria.
>So, for example:
>-I transform my E.Coli with my plasmid of interest in order that I can prep
>up large  amounts of the plasmid.
>- I would then use some of this plasmid to transfect my cells where I would
>then assay for its activity
>hope this helps :)
To some extent it is semantics, but it also has a history. In the 1940's, 
Avery's group was working on the phenomenon of the transformation of 
Staphylococcus (I think) from "rough" to "smooth" colonies. Eventually, they 
were able to show that this transformation was due to the uptake by "rough" 
bacteria of DNA from "smooth" ones, and by extension transformation has come 
to mean the change of phenotype by introduction of foreign DNA (the idea of 
"competent" cells also arose from this work). Transformation is therefore 
also correct to describe the transfer of foreign DNA into eucaryotic cells. 
However, transformation of eucaryotic cells also has also historically meant 
the event or events leading to the production of immortalised or cancerous 
cells. To avoid confusion, most people use the word transfection to describe 
the introduction of DNA into eucaryotic cells, although I don't know who 
coined the term.

I hope this helps.


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