# 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 µl pUC18 (0.1 ng/ µl)

50 µl E. coli competent cells

Left on ice 30 minutes

Heat shocked at 42C for 45 seconds

Added 500 µl NZY broth

Place in 15 ml culture tube in shaking incubator 37C for 1 hr

Then spread 10 µl, 50 µl and 100 µl on different LB amp plates.

10 µl 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 µl pUC18 (0.1 ng/ µl)

50 µl E. coli competent cells

Left on ice 30 minutes

Heat shocked at 42C for 45 seconds

Added 500 µl NZY broth

Place in 15 ml culture tube in shaking incubator 37C for 1 hr

Then spread 10 µl, 50 µl and 100 µl on different LB amp plates.

10 µl gave 495 colonies.

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

thanks!

-sc7-

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

5 µl pUC18 (0.1 ng/ µl)

50 µl E. coli competent cells

Left on ice 30 minutes

Heat shocked at 42C for 45 seconds

Added 500 µl NZY broth

Place in 15 ml culture tube in shaking incubator 37C for 1 hr

Then spread 10 µl, 50 µl and 100 µl on different LB amp plates.

10 µl 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 µg unit) you had in that 10µl you plated, which is not difficult.

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

-ProteinWork-