Overview & Purpose
Escherichia coli, commonly referred to as E. coli, has many different strains. The most commonly known serotypes of these bacteria can cause serious food poisoning or even fatality in humans. However, most strains are completely harmless. These strains are usually found in the gut of the host and help by producing K2 and helping with digestion. The presence of these bacteria is very beneficial for it helps to prevent pathogenic bacteria from being present in the intestine.
The Lac switch that we have created in the genetic coding of E. coli bacteria produces a glowing blue color that initially runs off of glucose and eventually runs off of lactose. With this technology, we can create a glow stick that can be used in emergency kits that will provide light in dire situations. By using a non-harmful strain of E. coli, we can create an environmental conscious and biodegradable glow stick that will not cause harm to the surroundings.
This technology will prove to be very helpful for hunters or those who are outdoors for they will not have to worry about disposing of their light source. Used like a regular glow stick, the different components of the device will remain separated and will be mixed together to produce light once a certain amount of force is applied.
Basic Components of a Lac Operon
Natural Lac Operon Parts/DNA Schematic 
The lac operon itself is a set of genes found in certain bacterias' DNA that is required for the transport and metabolism of lactose. Most commonly found in Escherichia coli, the operon was the first example of a group of genes under the control of an operator region to which a lactose repressor binds.
The Lac operon functions as a single transcription unit and is comprised of an operator, a promoter, and one or more structural genes such as a regulator or terminator that are transcribed into one polycistronic mRNA. When the bacteria are transferred to lactose-containing medium, allolactose (which forms when lactose is present in the cell) binds to the repressor, inhibits the binding of the repressor to the operator, and allows transcription of mRNA for enzymes involved in lactose metabolism and transport across the membrane.
The main idea is that E. coli (the most common medium when investigating the Lac operon) conserves its resources by not making Lac proteins when other more easily-accepted sugars, such as glucose, are available . This was tested by Jacques Monod during World War II. He tested the combinations of different sugars for E. coli and discovered that when the bacteria are grown with glucose and lactose, glucose would get metabolized first during the bacteria's growth phase I and then lactose during growth phase II. Thus, when these Lac proteins are made with the presence of lactose, the lac gene and its derivatives can be used to trigger a color change within the cell. Thus, once lactose is used up, glucose acts as the power source, and the lac operon can then act as a reporter gene.
Design: Our genetic circuit
OUR GENE SWITCH:
<tab>pSB1A3-1 is a high copy number plasmid. The replication origin is a pUC19-derived pMB1 (copy number of 100-300 per cell). The terminators bracketing pSB1A3 MCS are designed to prevent transcription from inside the MCS from reading out into the vector.
Building: Assembly Scheme
Testing: Modeling and GFP Imaging
A LAC SWITCH MODEL
We used a previously published synthetic switch, developed by Ceroni et al., to understand how our system could potentially be modeled and simulated.
AN INTERACTIVE MODEL
We used a model of the natural Lac operon to understand how changing the parameter values changes the behavior of the system.
COLLECTING IMPERICAL VALUES TO IMPROVE THE MODEL
We explored how one technique, imaging via microscopy could be used to determine the production rate of an output protein, in this case GFP in yeast, could be used to determine a "real" value for maximum GFP production rate under our own laboratory conditions.
- show plot of data and discuss outcome.
- include some of the pictures of the raw data
- wrap up section to explain how the curves could be improved
Ideally, the GFP production rate measured by this method could be entered as a value for [which parameter] in the Ceroni et al. model.
SUPPORTS & UNDERSTANDS
DOES NOT SUPPORT & UNDERSTANDS
SUPPORTS & DOES NOT UNDERSTAND
DOES NOT SUPPORT & DOES NOT UNDERSTAND
- My name is Emily Byrne, and I am a student majoring in biomedical engineering. I am taking BME 494 because ###. An interesting fact about me is that ###.
- My name is Sarah K. Halls, and I am a student majoring in Biomedical Engineering. I am taking BME 494 because I enjoy cell and tissue Engineering work and hope to start my career in this field of study. An interesting fact about me is that I did an internship at Harvard University working on cell patterning.
- My name is Edgil Hector (Sean), and I am a student majoring in biomedical engineering. I am taking BME 494 because the subject is relevant to my interests, and the class counts as a required technical elective. An interesting fact about me is that I am the most indecisive human being on the planet.
- My name is Julia Smith, and I am a senior majoring in Biomedical Engineering. I am taking BME 494 because I am extremely interested in synthetic biology. An interesting fact about me is that in addition to my nerdy side and love of accademic learning, I train reining horses.
 Potts, Michelle. "Microbiology Exam 2." Microbiology Exam 2. N.p., 12 Feb. 2012. Web. 24 Apr. 2013.
 Muller-Hill, Benno (1996). The lac Operon, a Short History of a Genetic Paradigm. Berlin: Walter de Gruyter. pp. 7–10. ISBN 3-11-014830-7.
 Full reference.