Biology 1202B Lecture Notes - Lecture 15: Histone H3, X-Inactivation, Methyl Group
14 Jul 2016
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Document Summary
Epigenetics: a phenomenon in which a change in gene expression is achieved without a change in the. Dna sequence of the gene or of the genome. All of these modification taken together, will decrease histone formation. Again, these modification all coming together will determine the compactness of the dna. Regulation at the level of transcription determines if the dna can be transcribed or not. Dna which is in heterochromatic form cannot be transcribed (turned off) Less active because their promoters are less accessible to the proteins that initiate transcription. Euchromatin means it is available to be turned on for transcription. For a eukaryotic gene to be activated, the chromatin structure must be altered in the area of the promoter to provide access to the general transcription factors for transcription initiation. All of these modification can be affected by environment (e. g. , cancer)
