Stress on the Lac-Operon Project

How Does Stress Affect Genetic Expression?

The "tool" that seems appropriate for doing this project is E.coli's lac-operon, which you have studied in your biology class. Just remember that you have studied only the "tip of the iceberg" of the lac-operon, and now you can delve deeper into it. For starters you should review what you were taught, and then look at what some other students did that seemed to indicate coincidentally and unintentionally that the lac-operon would be a good "tool" with which to start.

One group of students have opened the door onto this project. They were from Brooklyn NY, Erie, PA, and Decatur, TX, and collaborated using the internet and this webmaster to get the project done and shown to have reproducible results. They reasoned that stress should deleteriously impact on the ATP reserves of the cell, and this diminished [ATP] would cause the hyperexpression of the lac-operon. See where the enzyme adenyl cyclase plays a role in the expression of the lac-operon, then learn about how ATP affects that adenyl cyclase. Then you should think about what other sorts of stress you might subject upon your "poor, little" E.coli bacteria. It would be good to find stresses of both types - ATP requiring and those that don't require ATP. (Let's think of some stresses you might consider: extremes of pH, high [K⁺] or high [Na⁺], temperature, ...)* Thus, you should contact this webmaster with your thoughts, and they will be discussed back and forth with the webmaster several times, plans can be devised to pursue whichever method you choose, and continuing guidance can be given all the way through one or more presentations. Remember, there are no "cookbook" (established) methods for doing this. This website proposes original projects - you have to come up with the methods! It is strongly recommended that you work with the help of the webmaster and others in planning your procedures. This collaboration makes these projects good for presenting at real scientific society meetings (going far beyond "science fairs").

* One of the implications of this work is that monitoring the level of expression of the lac-operon will tell you whether or not various "pumps" in the cell's membrane require ATP, otherwise called "active transport." The last group studied osmotic stress caused by high levels of sucrose, a sugar that is not digestible by E.coli, and found that active transport is indeed involved in one or both the retention of water by the cell, or the exclusion of sucrose from the cell. They don't know which or whether it is both. So there's a project for you!

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