BIOL 202 Lecture Notes - Lecture 25: Organelle, Gigantism, Heteroplasmy
5 Nov 2015
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Document Summary
Inheritance doesn"t always follow mendel"s laws: epigenetic inheritance - position-effect variegation in drosophila, cytoplasmic inheritance - maternal-effect genes in drosophila. Histone acetylation hats (gcn5 complex) transcriptional activation (loosening nucleosome. Gene silencing, genomic imprinting: catalyzed by dna methyltransferase (dnmt) enzymes, occurs primarily on cytosine in cpg dinucleotide (mcpg, ~80% of cpg are methylated genome-wide, cpg methylation is not randomly distributed, cpg methylation. Correlated with repressed chromatin state (heterochromatin: cpg islands - cpg-rich clusters located near promoters (60% of genes, methylation of cpg islands is associated with repression/silencing of gene expression. March 11th, 2015: can be direct effect - blocks transcription factor binding, can also be indirect effect - due to effects on histone modifications, methyl-cpg-binding domain (mbd) proteins - bind specifically to methylated. Hemimethylation - methylation of one strand but not another: guided by methylation pattern on parental strand, unusual pattern of inheritance of the igf2 gene involved in embryonic growth.
