Assume that you added the same amount of lactose to two different cultures of E.
ID: 259163 • Letter: A
Question
Assume that you added the same amount of lactose to two different cultures of E.coli (the cultures contain different strains). There is no glucose in the media. Eighteen hours after glucose was added to the cultures, you assay the cultures for beta-galactosidase activity. The only data you collect are the absorbances of the assay at 420 nm. From these data, you conclude that each bacterium in one culture is producing five times more beta-galactosidase than each bacterium in the other cultures. Is your conclusion valid?
Explanation / Answer
The conclusion is valid because beta galactosidase is produced due to the addition of lactose in the medium. Lac operon also turned on when there is beta galactosidase. So, if you are taking the absorbance only at 420 nm, the results will be interpretable.