CHROMATIN. 100 trillion meters of DNA per human. Haploid human genome contains approximately 3 billion base pairs of DNA . each base pair is around 0.34 nanometers long. Each diploid cell therefore contains about 2 meters of DNA. Human body contains about 50 trillion cells.
100 trillion meters of DNA per human
A complex of nucleic acids and proteins (histones), which condenses to form a chromosome during cell division. cell nucleus …in eukaryotic cells,
Two each of the histones H2A, H2B, H3, and H4 come together to form a histone octamer,
which binds and wraps about 1.7 turns of DNA, 166bp.
nucleosomes are joined by 20 base pairs linker DNA
The packaging of DNA into nucleosomes shortens the fiber length about sevenfold
EPIGENETICS is the study of changes in gene expression or cellular phenotype, caused by mechanisms other than changes in the underlying DNA sequence.
EPIGENETIC TRAIT, "stably heritable phenotype resulting from changes in a chromosome without alterations in the DNA sequence"
CHROMATIN REMODELING: is the enzyme-assisted process to facilitate access of nucleosomal DNA by remodeling the structure, composition and positioning of nucleosomes.
Phosphorylation: modification of proteins in which a serine, a threonine or a tyrosine residue is phosphorylated by a protein kinase ,
A: a shorter more compact helical structure. occurs only in dehydrated samples of DNA, such as those used in crystallographic experiments
Z:left-handed helix with a zig-zag phosphate backbone , The major and minor grooves, unlike A- and B-DNA, show little difference in width