Ch18 - DNAPackaging...

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DNA Packaging Did you know that each cell in your body has almost  2 meters of DNA inside its little nucleus???!!! How does it fit???
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Chromatin :  DNA and its associated chromatin Euchromatin :  less tightly wound--is actively  transcribed So what kind of DNA would you find as  euchromatin??? Heterochromatin :  very tightly wound--not  accessible to transcription enzymes So what kind of DNA might you find as  heterochromatin???
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Histones  and  Nucleosomes 2 nm 10 nm DNA double helix Histone tails His- tones Linker DNA (“string”) Nucleosome (“bad”) Histone H1 (a) Nucleosomes (10-nm fiber) Nucleosome Protein scaffold 30 nm 300 nm 700 nm 1,400 nm (b) 30-nm fiber (c) Looped domains (300-nm fiber) (d) Metaphase chromosome Loops Scaffold
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Developmental Biology What makes you you? Nova: Life’s Greatest Miracle
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So, how do genes get  turned on and off? 1. Regulating chromatin  structure 2. Regulating  transcription  initiation 3. Post-transcriptional  regulation Signal NUCLEUS Chromatin Chromatin modification: DNA unpacking involving histone acetylation and DNA demethlation Gene DNA Gene available for transcription RNA Exon Transcription Primary transcript RNA processing Transport to cytoplasm Intron Cap mRNA in nucleus Tail CYTOPLASM mRNA in cytoplasm Degradation of mRNA Translation Polypetide Cleavage Chemical modification Transport to cellular destination Active protein Degradation of protein Degraded protein
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1.  Regulating  Chromatin  Structure Histone Acetylation -- unwinds chromatin DNA methylation --leads to  genomic imprinting
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This document was uploaded on 11/01/2011 for the course BIO 181 at BYU.

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Ch18 - DNAPackaging...

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