1. EURKARYOTIC DNA IS TIGHTLY PACKED AND HIGHLY ORGANIZED
Fig a
EURKARYOTIC DNA IS TIGHTLY PACKED AND HIGHLY ORGANIZED
Nucleosome
(10 nm in diameter)
DNA double helix (2 nm in diameter) H1
Histone tail
Histones
DNA, the double helix
Histones
Nucleosomes, or “beads on a string” (10-nm fiber)
-If fully stetched out a chromosome ( 200 million base pairs) would be 6 inches long
-DNA is tightly packed around proteins called histones so it will fit into nucleus

2. Figure 19.1 Levels of chromatin packing

3. Looped domains (300-nm fiber) Metaphase chromosome
Fig b
Chromatid
(700 nm)
30-nm fiber
Loops
Scaffold
300-nm fiber
Replicated chromosome (1,400 nm)
30-nm fiber
Looped domains (300-nm fiber)
Metaphase chromosome

4. The first level of DNA packing is the association of DNA with proteins called histones
Histones are + charged, DNA is – charged; complex of DNA wrapped 8 histones = nuclesome

5. Link to DNA structure animation
Interactive DNA ; Animations:
1) Chromosomes 2) DNA packaging
3) How much DNA codes for protein?
Coding vs. Noncoding- Jim Kent
Bacterial vs. Human – Eric Lander
Chromosome 11 Flyover