AP Biology students transform the bacterium E. coli using gene for green fluorescent protein
Last week, students in AP Biology learned how DNA can be transferred to another organism and the change in phenotype (physical characteristics) that may result from such a transfer.
In molecular biology, transformation refers to a form of genetic exchange in which the genetic material carried by an individual cell is altered by incorporation of foreign (exogenous) DNA. This foreign DNA may be derived from unrelated species and even other kingdoms, such as bacteria, fungi, plants or animals, which would otherwise be inaccessible to an organism.
Students transformed E.coli, which lives in the human gut and is a relatively simple and well understood organism. Its genetic material consists mostly of one large circle of DNA 3-5 million base pairs in length, with small loops of DNA called plasmids, usually ranging from 5,000-10,000 base pairs in length, present in the cytoplasm. It is these plasmids that bacteria can transfer back and forth, allowing them to share genes among one another and thus to naturally adapt to new environments.
In this lab, Green Fluorescent Protein (GFP) from the bioluminescent jellyfish Aequorea victoria was incorporated into a plasmid along with a gene for resistance to the antibiotic ampicillin. When inserted into a plasmid and used for the transformation procedure, the transformed bacteria expressed their newly acquired jellyfish gene and produced the fluorescent protein, which caused them to glow green under ultraviolet light. The mutant form of GFP used in pGREEN makes the bacteria a yellow-green color even in white light.
Check out photos of the lab below!