Biology 2581B Lecture 14: Epigenetic variation
1 Mar 2019
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Document Summary
Epigenetic refers to alterations in chromatin structure/expression that: persist beyond their initial creation, do not involve changes in dna sequence. Examples: bees: one sister develops into queen, other into a sterile worker, humans: mother wants small baby, father wants big baby, cats: x inactivation, dosage compensation, plants: plant flowering responds to environmental cues. Implication of dna methylation at cpg islands for gene expression. Embryonic stem cell progeny differentiate into myriad cell types (epigenetics) Hemimethylation: cytosines on old strand will be methylated, cytosines on new strand will not be (epigenetic marks are maintained through replication: opportunity to do excision repair + to know which base is the correct base. Basic mechanism of epigenetic regulation of queen vs. worker development. Methylation is an important aspect in maintaining casts in insects. Acetylation of histones opens them up, opens up chromatin, opens nucleosomes and increases expression. Methylation of dna is different than methylation of histones. Histone deacetylase (hdac) tend to block transcription.
