Chromatin is a genetic material or a macromolecule comprising of DNA, RNA, and associated proteins, which constitute chromosomes in the nucleus of a eukaryotic cell. It is located within the cell nucleus.
Functions of Chromatin 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.
When looked through a microscope, It looks like beads fitted in the string. These beads are known as nucleosomes. The nucleosome itself is composed of eight proteins known as histones. The nucleosomes form a solenoid by wrapping themselves into a 30nm spiral. 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 structure.
Structure of Chromatin
The structure is governed by several 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 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 the 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.
Difference between Chromosome and Chromatin
|Chromosomes are condensed Chromatin Fibers.||It is composed of a nucleosomes-a complex of DNA and proteins.|
|Chromosomes are thick, compact, and have a ribbon-like shape||It is a thin and long fiber|
|Distinctly visible during cell division.||Found throughout the cell cycle.|