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Multiple Choice
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
Transcription factors
E
Allolactose
Verified step by step guidance
1
Understand the function of the lactose operon in E. coli: The lactose operon is a set of genes that are involved in the metabolism of lactose. It is regulated by the presence or absence of lactose in the environment.
Identify the role of allolactose: Allolactose is an isomer of lactose that acts as an inducer in the lactose operon. It binds to the repressor protein, causing it to change shape and release from the operator region, allowing transcription to proceed.
Recognize the genetic modification: In this scenario, the structural genes of the lactose operon have been replaced with the gene for human growth factor. This means that the production of human growth factor is now under the control of the lactose operon.
Determine the substance needed to induce the operon: Since allolactose is the natural inducer of the lactose operon, adding allolactose to the culture will bind to the repressor protein, allowing transcription of the inserted human growth factor gene.
Conclude the process: By adding allolactose to the bacterial culture, you effectively induce the operon, leading to the production of human growth factor by the bacteria.