Monday, 30 January 2012

Gene expression of the lac operon using IPTG


To show how genes can be regulated by using the lac operon as an example.


BL21 (DE3) + egfp (un-induced)
3 agar plates with Kanamycin
0.5 mM IPTG

Plate 2 kanamycin plates with un-induced BL21(DE3) + egfp.
Label plates no IPTG and IPTG
Place in 37°C incubator overnight
To turn gene on for expression
Plate 1: Do not add anything
Plate 2: Using a sterile pipette tip, add 8 µL 0.5 mM IPTG per colony.
Allow IPTG to soak in
Incubate at 37°C overnight
Place the plate under UV light to see bacteria glow.
Calculation: To make 0.5 mM IPTG, mix 50 µL 1.0 M IPTG + 50 µL LB broth
This would be a cool extension of this lab that might be more relatable to the students.

Lab by Ingrid Coulson,
9th grade Honors Biology teacher
Broughton High School, Raleigh, NC

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