HMB265H1 Lecture Notes - Lecture 19: Dna Methyltransferase, Methyl Group, Phosphodiester Bond
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HMB265H1 Full Course Notes
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Dna methylation at cpg islands silences gene expression: cpg islands= a regulatory element of some eukaryotic genes, which is unusually rich in. If activators aren"t there any more then cpg islands become methylated. Homozygous for a2: when passed on to the offspring they only express a1 because a2 was imprinted= inactivated, expression of allele depends on the parent that transmits it. In genomic imprinting, the copy of a gene an individual inherits from one parent is transcriptionally inactive while the copy inherited from the other parent is active. If deletion is passed from man to child, both sons and daughters would each have 50% chance of receiving a deleted paternal allele. Dna methylation must be reset during meiosis before being passed on to the next generation. If this were not true, the imprinting would not be sex-specific: those children would express the mutant phenotype, b/c intact copy inherited from their mother is inactive.
