Early or late owering more flcless flowering takes

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Unformatted text preview: ation = more This leads to reduced FLC expression Question Text What should the phenotype of an fld mutant be? (Early or late flowering?) more flc=less flowering, takes longer before flowing occurs inc flc=dec flow (early flowering) Histone Acetylation Addition of acetyl groups to histone tails Stimulates transcription by causing DNA and histones to bind less tightly causes dna unwinding Chromatin Remodeling Complexes Protein complexes that reposition nucleosomes without altering histone structure Usually activate transcription Example: SWI-SNF complex can expose promoters by changing the position of nucleosomes along the DNA when promoter is less wrapped, activator is activated more easily DNA Methylation The addition of methyl groups to cytosine bases to yield 5methylcytosine (5-mC) Methylated DNA is usually silent, while transcriptionally active DNA is unmethylated 5-mC is most often to be found adjacent to guanine nucleotides (CpG islands) Epigenetic Effects methylation of dna can effect epigenetic effects Epigenetic effects: long-term changes in chromatin structure that result in heritable changes in gene expression NOT a result of change in DNA sequence Thus, environmental effects CAN result in heritable changes in gene expression turn one x chromosome off is accomlished by epigenetic effects Example: Maternal Behavior in Rats Offspring of mother rats that display more grooming behaviors (towards the pups) are: less fearful have reduced stress measured by cortisol levels Example: Maternal Behavior in Rats Offspring of mother rats that display more grooming behaviors (towards the pups): show changes in DNA methylation and histone acetylation which results in altered gene expression (glucocorticoid receptor gene) These changes can be prevented by treating pups with a histone deacetylase inhibitor when treated, mice end up having traits as if they were raised by bad mom mice Transcriptional Control: Promoters • Promoters: sequences required to initiate transcription – Immediately adjacent to (and 5’ of) gene no operons – Specify where transcription begins and directionality • Eukaryotic promoters are modular: – TATA box (“core promoter”) (-25 to -30): binds RNA upstream polymerase;...
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This document was uploaded on 02/25/2014.

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