(3) Below is a diagram of a human gene X whose expression is regulated by the en
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(3) Below is a diagram of a human gene X whose expression is regulated by the enhancer shown; this enhancer has binding sites for transcription factors A and B. The table on the right shows the expression of mRNA from the genes that encode these two transcription factors and gene X in four different tissues Tissue A mRNA BmRNA XmRNA ? ??? Heart Liver Pancreas un yes yes yes yes no yes no yes yes no no yes enhancer gene X (a) Explain the results in the table (i) What type of transcription factor is A most likely to be?: (ii) What type of transcription factor is B most likely to be?: (ii) Explain why X is expressed in the heart (iv) Explain why X is not expressed in the liver: (v) Explain why X is not expressed in the pancreas: (vi) Explain why X is expressed in the lung (b) If the region containing just the coding region of gene X was inverted (as shown below) in relation to the enhancer, what effect would this have on its expression in these tissues? B ABA enhancer (c) Expression of these genes and the genomic region containing gene X were investigated in pigs and it was shown that the sequence of this enhancer was quite strongly conserved with all of the binding sites for A and B still present. However, curiously, gene X was now expressed in the liver. Provide a possible explanation.Explanation / Answer
a)
i)FOXM1 is expressed in actively dividing cells.
ii) FOXA1/2 induces cell proloferation , branching morphogenesis, and epithelial cell differentiation it plays a central role in lung and liver development.
ii) x is FOXO3 Which activates connective tissue cells.
b) no it will have the same effect.
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