1. You are studying two closely related species of bacteria (species A and speci
ID: 269591 • Letter: 1
Question
1. You are studying two closely related species of bacteria (species A and species B). When both species are grow at room temperature they form white colonies and when they're grown at 37°C the colonies are red. You have cloned the gene for the pigment (pigment X) that causes the red color at 370 from both species and have found that the ORF encoding pigment Xis identical in DNA sequen both species. You next perform a Northern Blot to see how the expression of pigmentX is regulated. You isolate RNA from both species grown at room temperature and at 370C and use labeled DNA from the cloned gene as your probe to generate the results shown below: nce in Species RT 37ec RT 37C ep licated altenative splicin A. At which level of gene expression is pigment production controlled in species A? Briefly explain your answer. B. At which level of gene expression is pigment production controlled in species B? (Hint: there are at least 3) Briefly explain your answer what sort of further analysis would you perform to distinguish between the possible explanations for the data obtained from species B? C. Westein BlotExplanation / Answer
1)- A) In species A, the gene expression of pigment X is regulated at the transcriptional level. The proof is the northern blot, at RT no or very less transcript for the gene X is detected. A huge amount of transcript is detected at 37C, indicating gene expression is regulated by the temperature at the transcriptional level.
B) In species B, Since the transcript is present at both the conditions so the gene is not regulated at the transcriptional level. Since it is bacteria, fewer chances of alternative splicing. Also, northern blot detects no change in transcript size in two conditions. There are several other possibilities.
p) However, the regulation could be at translational level. m-RNA is kept sequestered from associating with ribosomes. The secondary structure of the m-RNA is hiding the translation signals. So protein X is not made for pigment synthesis.
q) Protein is made but is inactive. This can be due to post-translational modification of the protein that may activate or inhibit the protein activity. Protein can be inactive due to improper folding as well.
r) protein is kept sequestered in a compartment. Moved to correct compartment only at 37C where the precursor is present.
C) p) western blotting at two temperatures will confirm the regulation at translation level or post-translational modification.
q) By studying in vitro protein folding, the possibility of change in folding status can be known.
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