DNA packaging
- Created by: Ellie0o0o
- Created on: 27-04-15 15:39
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- DNA Packaging
- Chromatin
- Euchromatin
- Loosely packed
- Replicated early in the S phase
- Found in nucleus centre
- Heterochromatin
- Replicated later
- Tightly packed
- Found at the nucleus periphery
- Tends to hold oncogenes, telomeres, centromeres and transposons
- Euchromatin
- "Beads on a string"
- A series of nucleosomes
- = 4 histone proteins + 146bp DNA
- Histone
- Octamer
- Monomers are...
- Small: 100-140 aas
- 2x H2A
- 2x H2B
- 2x H3
- 2x H4
- BASIC
- A partial +ve charge allows DNA association
- Monomers are...
- H1
- Linker histone, joins nucleosomes
- Octamer
- Histone
- = 4 histone proteins + 146bp DNA
- A series of nucleosomes
- 30nm Fiber
- Beads on a string further compacted
- Formed by H1 linking nucleosomes
- Though levels of packaging vary, naked DNA is rare
- It signals a problem such as viral DNA
- The less packaged the DNA, the more vulnerable it is to DNase
- Additionally affected by
- Histone modifications
- Chromatin remodelling complexes
- DNA methylation
- Packaging is a major difference between pro- and eukaryote DNA
- No packing mean no block to transcription
- Chromatin
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