# What amount of insert:vector should I use if I want a 3:1 molar ratio? - (Apr/24/2006 )

Hi all,

I'm doing some cloning experiments now and I wanted to make sure how to calculate how much insert and vector I need. My insert is 110bp and my vector is 8kb and I want a 3:1 molar ratio of insert to vector. The way I was taught was that since my vector is 80 times bigger than my insert, I divide 3 by 80 (which is 0.0375) and that is how much more insert I need than vector. That's what I was told which I think is incorrect because that means the larger the vector is compared to the insert , the less insert we need. I thought it was the other way around? Can someone please confirm for me? So if I have 6ng/ul of insert and 10ng/ul of vector...how many ng of vector would I need per 6ng of insert? It's my first time, please help!

Selenilum

-selenilum-

Here you have the formule given by Promega for pTarget. In this case, the size of the plasmid is 5.7kb (60ng/ul) and the insert 0.8kb. Make the appropriate changes for your experiments.

To do this, you need to know how much amount you got of each (vector and insert).

-gsamsa-

Hi Gsamsa,

Thanks so much for your reply. I think that was the equation I used as well, just wanted to make sure.

-selenilum-