Sp09MicroLab9Phenotype - The other crosses that caused a...

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University of Texas at Austin Bio126L Course Instructor: Pratihba Saxena Spring 2009 Lab 9: Phenotypic Changes Purpose To observe phenotypic variation due to environment or mutation and the significance of cross-feeding. Discussion The white color of the S. marcescens slants when incubated at 37C is due to the organism not producing prodigiosin at the higher temperature. The organism turns pink again when incubated at 25C because it is able to produce prodigiosin again. Since this change is variable this means that there has not been a change in the genetic code of the organism. I did my cross feeding using the #4 and #5 mutants. The #5 mutant must have produced an upstream product that #4 could use because #4 was able to produce the pink pigment whereas it would normally not (it would be white if it was not plate with the #5 mutant).
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Unformatted text preview: The other crosses that caused a mutant to be able to produce the pigment were: 1x2, 1x3, 1x5, 2x3, 2x4, 3x4 and mine, which was 4x5. In the 1x2, 1x3 and 1x5 crosses the #1 strain is the mutant, which is cross-fed causing it to produce the pink pigment (it would normally be white). Since the #1 mutant can be fed by mutants 2, 3 and 5 this means that #1s mutation is earlier in the pathway. In the 2x4, 3x4 and 4x5 crosses, the #4 mutant (which is normally white) was able to produce the pink pigment. This means that #4 also has a mutation earlier in the pathway than the mutations that occur in 2, 3, and 5. The 2x3 cross is different in that the mutant, #3, which is cross-fed is normally peach (instead of white) meaning it can produce the nonprodigiosin pigment....
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