chapter 19 - How are Eukaryotic Genomes Organized?...

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1 How are Eukaryotic Genomes Organized? Regulated? How do they evolve? DNA in a eukaryotic chromosome developing salamander egg DNA sequences in the human genome Exons (regions of genes coding for protein, rRNA, or tRNA) ( 1.5% ) Introns and regulatory gene sequences ( 24% ) Repetitive DNA that includes transposable elements and related sequences Alu elements common to primates (10%) Simple sequence DNA (3%) Large-segment duplications (5–6%) Unique noncoding DNA (15%) (44%) Repetitive DNA unrelated to transposable elements (about 15%) 3.4 nm 1 nm 0.34 nm Nucleosomes Æ DNA and histone proteins form beads ” for chromatin packing during cell interphase DNA double helix 2 nm Histone tails His- tones Linker DNA (“string”) Nucleosome (“bead”) 10 nm Histone H1 Nucleosomes (10-nm fiber) 30 nm String of nucleosomes coils during cell interphase Nucleosome 30-nm fiber
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2 300 nm Protein scaffold Folding of DNA into looped domains during prophase . Loops attached to non-histones (scaffold) Looped domains (300-nm fiber) Loops Scaffold Metaphase chromosome 700 nm Compacted chromatin in a metaphase chromosome 1,400 nm Signal NUCLEUS DNA RNA Chromatin Gene available for transcription Gene Exon Intro Transcription Primary transcript RNA processing Cap Tail mRNA in nucleus Transport to cytoplasm Chromatin modification: DNA unpacking involving histone acetylation and DNA demethylation hetero-chromatin eu-chromatin CYTOPLASM mRNA in cytoplasm Translation Degradation of mRNA Polypeptide Cleavage Chemical modification Transport to cel ular destination Degradation of protein Active protein Degraded protein from DNA to proteins a complex process Enhancer (distal control elements) Proximal
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This note was uploaded on 04/16/2008 for the course BIO 131 taught by Professor Paz y mino during the Fall '08 term at UMass Dartmouth.

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chapter 19 - How are Eukaryotic Genomes Organized?...

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