Dr Karzan Mohammad Chromatin Eukaryotic DNA is closely associated with proteins creating chromatin Of two types Heterochromatin Euchromatin Chromatin Euchromatin Actively transcribed ID: 914116
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Slide1
The Chromatin and genome packaging
Dr.
Karzan Mohammad
Slide2Slide3Slide4Chromatin
Eukaryotic DNA is closely associated with
proteins,
creating
chromatin.
Of two types:
Heterochromatin
Euchromatin
Slide5Chromatin
Euchromatin
Actively transcribed
Loosen packaging
Regulated by proteins
Found along the chromosome arms
Slide6Chromatin
Heterochromatin
Poorly transcribed
Tighten packaging
Regulated by proteins
Found specially in centromeres and telomeres
Slide7Slide8Histones
Positively charged
a high percentage of arginine and
lysine
Slide9Histones
Slide10Non Histone proteins
Scaffold proteins
chromosomal protein “skeleton
”
Role in packaging
High-mobility-group proteins Role in packaging and
unpackaging
during transcription
Other non histone proteins
Polymerase
Helicase
Primase
Slide11Nucleosome
Beads on string
DNA 2 times around histone
Together, the core particle and its associated H1 histone are called the
chromatosome
,The H1 protein is attached to between 20 and 22 bp
of DNA, and the nucleosome encompasses an additional 145 to 147
bp
of DNA; so about 167
bp
of DNA are held within the
chromatosome
.
Slide12Slide13