Definition
Definition
Chromatin is the substance used to create chromosomes.
She is made of :
- DNA molecules.
- RNA molecules.
- Of proteins.
History
Chromatin is a substance described by Miescher in 1869 and named by Fleming in 1882.
Symptoms
physiology
Chromatin is arranged in the cell nucleus in the form of networks. It is primarily composed of:
- D'Deoxyribonucleic acid.
- De protein called histones.
Chromatin transforms into chromosomes during cell division ( mitosis ) ; it is the carrier of heredity.
More specifically, chromatin is made up of a skein of fibers that stain relatively well, but irregularly, allowing it to be highlighted in the nucleus. It contains roughly equal amounts of DNA , representing the cell's genetic material .
Chromatin also contains:
- The histones, which are globular proteins.
- Des nucleosomes (nucleus body), which are the fundamental units of the chromatinThese are clusters of globular shapes of eight histones, resembling beads strung on a string, and connected by a DNA molecule wrapping itself around each of these globular clusters. In other words, the role of histones is to allow the very tight, but orderly, folding of long DNA chains.
When the cell is about to divide, the chromatin strands coil and condense very tightly. This results in small rod-shaped structures called chromosomes (colored bodies). This is how the DNA strand increases to 10,000 times its original length.