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    Deviation in color of E.coli colonies after exposure to UV light.

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    We are suppose to explain what type of mutation could cause for color variation in certain colonies of E. coli. We first started off with one normal strand of the E. coli bacteria, and after UV light exposure we need to propose a theory of what typeof mutation could cause a single colony to mutate into 5 possible colors (white, pink, orange, red, and dark red).

    We also need to know if this mutation could be related somehow to dna repair mechanisms and if they can somehow link to other mutations.

    We also noted delayed growth in some of the colonies, ie. after 2 days there was no growth but after 4 there was.

    Also, why do they grow in sectioned colonies instead of all together.

    Now, I have come up with a few theories on my own. We know that there are certain dimer mutations that include thymine - thymine, but we have to have a relatively simple explanation of how a single mutation can relate with DNA repair and other mutations to cause a single strand of E. coli to change into those 5 different colors.

    I have also thought that the insertion of a transposon into an exon: get no expression in all cells descending from the insertion event AND if there was an insertion of one into an intron: there will be altered expression in all cells descending from the insertion event .. But i am not sure if that constitues a mutation. OUR teacher says that it is a lot easier to explain than how i am gonig about it, but he wont help any of the kids. We have already filed a complaint about him to the Biologoy board, and they are sitting in on his classes and i have heard that he will not be around much longer, however this doesn't help our grade. I was told that Organic chem was supppose to be the hardest class that I will take in my few years here...well i have an A easily in Organic Chem, however the teacher we were suppose to have died 4 months before our class started and we have a man who has never taught before and he isnt very good.

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    Solution Preview

    Well, your teacher is right. It is a lot easier to explain than what you're trying to come up with! But that's okay. It's all part of the learning process.

    All the teacher is asking for is a hypothesized mechanism that can explain how X-rays can cause mutations to such an extent that E. coli colonies grow in a multitude of colors.

    Question: What does X-rays do to DNA? Back in 1927, H.J. Muller won the Nobel Prize for demonstrating that X-rays can cause mutations. He blasted fruit flies with varying doses of X-rays and then observed their progeny. X-rays greatly increased the occurrence of mutations and, in addition, the inheritance patterns of those mutations were the same as for spontaneous or natural mutations.

    What are some types of mutations that X-rays can cause?

    X-rays can cause all kinds of DNA damage, even breaks in one or both strands. These breaks can lead to rearrangements, additions, deletions, etc. In addition, X-rays can induce damage or loss of nucleotides (bases). And, X-rays can even cause crosslinking of DNA to itself or to proteins. Essentially, X-rays are bad news. (You might want to say "No" to your dentist next time he gets excited about blasting away at your mouth!)

    But, let's keep it ...

    Solution Summary

    The hypothesis of the deviation in color for E.coli colonies after exposure to UV light is found. The delayed growth of this mutation is determined.