# plasmid molar concetration/copy number - (Feb/28/2007 )

Hi all,

I hope someone can help. I have a school student who wants to do a short 2 day work experience program. Basically, she wants to see if larger plasmids transform at a lower rate than smaller plasmids. To keep it simple, I have a plasmid of 33 kb and a plasmid of 3 kb. In my mind, it would be necessary to work out the molar concentration of the plasmid so that when comparing the two she is adding equal amounts in copy number. That is, that she is adding approximately the same copies of plasmid in the transformation.

Is it something as simple as having to add 10 times more of the 33 kb since it is 10 times larger or have I got it wrong? Any feedback would useful. Thanks.

ML1975

I think that's probably right

the place where you will run into difficulty is not necessarily the size, but difference in conformation of the plasmid

nicked, supercoiled, etc will not necessarily transform with the same efficiency. is there any other sort of secondary structure to worry about?

the place where you will run into difficulty is not necessarily the size, but difference in conformation of the plasmid

nicked, supercoiled, etc will not necessarily transform with the same efficiency. is there any other sort of secondary structure to worry about?

Hi Aimikins,

Thanks for your reply. So the supercoiled being the smallest transforms the best? And the other forms are less likely to transform as well...is that the theory? I can't think of a way to get around the problem but its not big deal, it is just a small student project so I am not too upset about it.

ML1975