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help with transformation efficiency calculation! - (Apr/20/2010 )

Hi
im having trouble calculating the transformation efficiency for the competent cells. this is what i was given:

5 l pUC18 (0.1 ng/ l)
50 l E. coli competent cells
Left on ice 30 minutes
Heat shocked at 42C for 45 seconds
Added 500 l NZY broth
Place in 15 ml culture tube in shaking incubator 37C for 1 hr
Then spread 10 l, 50 l and 100 l on different LB amp plates.

10 l gave 495 colonies.

would really appreciate it if someone could help me out, the answer should be in cfg/ug units

thanks!
-sc7-

-sc7-

sc7 on Apr 20 2010, 04:51 PM said:

Hi
im having trouble calculating the transformation efficiency for the competent cells. this is what i was given:

5 l pUC18 (0.1 ng/ l)
50 l E. coli competent cells
Left on ice 30 minutes
Heat shocked at 42C for 45 seconds
Added 500 l NZY broth
Place in 15 ml culture tube in shaking incubator 37C for 1 hr
Then spread 10 l, 50 l and 100 l on different LB amp plates.

10 l gave 495 colonies.

would really appreciate it if someone could help me out, the answer should be in cfg/ug units

thanks!
-sc7-

This sounds like a homework question. You should probably go to the homework question forum if that is the case.

Anyway, the key is to calculate how much DNA (in g unit) you had in that 10l you plated, which is not difficult.

And I believe the unit should be cfu/g, in which cfu means Colony Forming Unit.

-ProteinWork-