The Interaction between Genes and Environment Look again at the four plates. Do
ID: 270851 • Letter: T
Question
The Interaction between Genes and Environment Look again at the four plates. Do you observe some E. colil growing on the LB plate that does not contain ampicilin or arabinose? 1. From your results, can you tell if these bacteria are ampicillin resistant by looking at them on the LB plate? Explain your answer 2. What might happen to these bacteria if you moved them to plates containing ampicillin? 3. Often an organism's traits are caused by a combination of its genes and its environment. Think about the green color you savw in the genetically transformed bacteria as you consider these questions a) What two factors must be present in the bacteria's environment for you to see the green color? b) Provide another example of a change in the environment causing expression of a different trait. What advantage would there be for an organism to be able to turn on or off particular genes in response to certain conditions? c)Explanation / Answer
1) Yes. The bacteria that did not receive the plasmid are growing on a plain LB plate.
2) The bacteria will not grow. The bacteria did not receive the plasmid which is ampicillin resistant. So, the bacteria will not able to grow on plates containing ampicillin.
3) The sugar arabinose in the agarose plate is needed to turn on the expression of the GFP gene. The UV light is necessary to cause the GFP protein within the bacteria to fluoresce.
4) The change of the bacteria's environment can tell us if they are ampicillin resistant or not. Take some of the bacteria growing on the LB plate and streak them on an LB/amp plate. If the bacteria are viable on the LB/amp plate, then they are resistant to ampicillin. If no bacterial colonies survive then they were not ampicillin resistant (they were ampicillin sensitive).
5) Gene regulation allows for adaptation to differing conditions and prevents wasteful overproduction of unneeded proteins. Good examples of highly regulatable genes are the enzymes which break down carbohydrate food sources. If the sugar arabinose is present in the growth medium it is beneficial for bacteria to produce the enzymes necessary to catabolize the sugar source. Conversely, if arabinose is not present in the nutrient media, it would be waste of energy to produce the enzymes to break down arabinose.
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