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Biotechnology & pGLO Transformation Lab
Information for this lab is taken from BIORAD’s “Biotechnology Exploreer pGLO Bacterial
Transformation Kit Catalog Number 166-0003EDU”.
Consideration 1: Gene Regulation
Our bodies contain thousands of different proteins which perform many different
jobs. Digestive enzymes are proteins; some of the hormone signals that run through our
bodies and the antibodies protecting us from disease are proteins. The information for
assembling a protein is carried in our DNA. The section of DNA which contains the
code for making a protein is called a gene. There are over 30,000 – 100,000 genes in the
human genome. Each gene codes for a unique protein: one gene, one protein. The gene
that codes for a digestive enzyme in your mouth is different from one that codes for an
antibody or the pigment that colors your eyes.
Organisms regulate expression of their genes and ultimately the amounts and
kinds of proteins present within their cells for a myriad of reasons, including
developmental changes, cellular specialization, and adaptation to the environment. Gene
regulation not only allows for adaptation to differing conditions, but also prevents
wasteful overproduction of unneeded proteins which would put the organism at a
competitive disadvantage. For example, the simple sugar arabinose is both a source of
energy and a source of carbon for bacteria. The bacterial genes that make digestive
enzymes to break down arabinose are not expressed when arabinose is not present in the
environment. When arabinose is present, these genes are turned “on”. When the
arabinose runs out in the environment, the genes are turned off again.
Arabinose initiates the transcription of these genes by promoting the binding of
RNA polymerase. In the genetically engineered the DNA code of the pGLO plasmid,
some of the genes involved in the breakdown of arabinose have been replaced by a
jellyfish gene that codes for Green Fluorescent Protein (GFP). When the bacteria that
have been transformed by the pGLO plasmid are grown in arabinose, the gene encoding
GFP is turned on and bacteria colonies glow brilliant green when exposed to UV light.
The pGLO plasmid which contains the GFP gene also contains the gene for beta
lactamase, which allows the bacteria to be resistant to the antibiotic ampicillin.
This is an excellent example of central molecular framework of biology in action:
DNA
RNA
Protein
Trait
BIO9 - Spring 2009
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