Chromatin: Spiraling a life!
Chromatin is a substance within a chromosome consisting of DNA and protein. The DNA carries the cell's genetic instructions. The major proteins in chromatin are histones, which help package the DNA in a compact form that fits in the cell nucleus. Changes in chromatin structure are associated with DNA replication and gene expression.
Chromatin is the material that makes up a chromosome that consists of DNA and protein. The major proteins in chromatin are proteins called histones. They act as packaging elements for the DNA. The reason that chromatin is important is that it's a pretty good packing trick to get all the DNA inside a cell. If one took the DNA inside of one cell and stretched it out end to end, it would be about a yard long. Each cell is about a hundredth of a millimeter across, so it's pretty good packing job for the yard of DNA within something that is a hundredth of a millimeter in diameter. And the chromatin does that by wrapping and re-wrapping the DNA in a very tight coil. And that arrangement is called chromatin.
This chromatin is located within the cell nucleus. The main functions of this genetic material include:
- Preventing DNA damage.
- Tightly packing of the DNA to fit into the cell.
- Control the DNA replication and gene expression.
- Support the DNA molecule to permit the process of cell cycle – meiosis and mitosis.
The structure of chromatin or the so-called nucleosomes resembles the arrangement of string on beads when observed under the light microscope in its elongated method. Each nucleosome comprises DNA, which is wrapped with eight proteins termed histones. Later, these nucleosomes are enfolded into 30 nm coiled named solenoid. Therefore the presence of histone proteins helps in supporting the chromatin structure.
Structure of Chromatin
The structure of chromatin is governed by a number of factors. The complete structure mainly depends on the phases of the cell cycle. They undergo various structural changes during cell division. The structure of chromosomes is clearly visible under a light microscope during metaphase, which changes their shape while the DNA is duplicated and divided into two cells.
There are 3 stages in chromatin group:
- Nucleosomes are formed by the wrapping of DNA around the histone proteins
- Multiple histones wrap into a 30 nm fiber consisting of the nucleosome.
- Higher-level DNA packaging of the 30 nm fiber into the metaphase chromosome.
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