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Plasmid Function


One can use DNA transformation as a laboratory method to study regulation of gene expression. One such system frequently used in high school biology is the genetically engineered plasmid, pGLO, which incorporates parts of the arabinose operon to drive the expression of green fluorescent protein (GFP).

Created for Albert.io. Copyright 2016. All rights reserved.

In the absence of arabinose, the regulatory protein ara C will bind to the operator region (O) of the ara operon and prevent transcription of the downstream genes, ara B, A and D. When present, arabinose will bind to ara C, changing its role to one that facilitates transcription and expression of the aforementioned genes, leading to the expression of proteins involved in the digestion of arabinose.

In the case of the pGLO plasmid, the GFP gene has been swapped in for ara B, A and D positioned behind the promoter that drives the transcription of ara B, A and D. A $\beta$-lactamase gene (bla) is included for antibiotic selection. The U-turn arrows on the ends indicate the circular nature of the plasmid.

If one were interested in driving the expression of insulin under the control of arabinose exposure, in which of the following regions would the insulin gene be placed?




ara C