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13 Cards in this Set
- Front
- Back
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Heterochromatin
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functionally inactive DNA
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Euchromatin
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active DNA
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Nucleosome
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fundamental subunit of chromatin
146 bp with an octamer of basic prots (histones) charge interaction between + histones and - DNA coiling into a helical array 30 nm diameter, packing ~40 |
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Nucleosome
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11S particle
146 bp DNA + 2 x(H2A, H2B, H3, H4) core histones H3/H4 most conserved H2A/2B show variation H1 linker histone DNA wraps around twice |
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H1
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histone binds the outside of core nucleosomes and further compacts DNA
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Metaphase
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chromosomes condensed (compact)
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Interphase
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chromosomes decondensed (accessible)
gene expression |
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Genes near heterochromatin
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inactive if not insulated
depending on where the gene is located its expression will either be silenced or activated |
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Epigenetic control
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the control is not related to the DNA sequence
brought about by the modifications of DNA bases and histones |
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Imprinting
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plays a role in gene regulation
one of the 2 alleles is expressed and the other is imprinted (inactive or not transcribed) imprinted genes are not expressed epigenetic control, not at the level of the DNA seq |
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PWS
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deletion inherited by dad, maternal allele of the gene is imprinted
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AS
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deletion inherited by mom, paternal copy of the gene is imprinted
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Resetting of imprints occurs where?
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cellular machinery erases old imprints and establishes new ones in germ cells during meiosis
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