You have inserted the gene for human growth factor into the E. coli lactose operon, replacing the structural genes with the gene for human growth factor.
What substance must you add to your culture of bacteria to cause them to produce human growth factor for you?

a) repressor protein
b) operator protein
c) human growth factor
d) lactose
e) Any of the above substances will work

d) lactose

Explanation:

Based on the scenario being described within the question it can be said that the substance that you should add in order to accomplish this would be lactose, more importantly Allolactose. This is because this is an inducer, meaning it turns on (induces) the lac genes which in term causes a conformational change and in this scenario produce the human growth factor needed.

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