lec 17 - Lecture 17 Chromatin structure Cover...

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Lecture 17: Chromatin structure Cover photograph (Copyright © 2007, American Society for Microbiology. All Rights Reserved.): Atomic force microscopy (AFM) images of individual molecules of chromatin showing compaction by the nucleosome-binding enzyme poly(ADP-ribose) polymerase 1 (PARP-1). Chromatin was assembled in vitro using an ׽ 10.5-kb circular plasmid. The images shown are chromatin alone (top), chromatin after the addition of PARP-1 (middle), and chromatin after the sequential addition of PARP-1 and NAD + (bottom). The addition of NAD + promotes the auto(ADP-ribosyl)ation of PARP-1, the release of PARP-1 from nucleosomes, and the decondensation of chromatin. The AFM images were obtained in the amplitude mode. (See related article on p. 7475 .)
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In Eukaryotes, DNA is associated with proteins -> nucleoprotein complex = chromatin Major protein components: histones Chromatin Electron microscope
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