What Is Chromatin?
Chromatin is a genetic material or a macromolecule comprising of DNA, RNA, and associated proteins, which constitute chromosomes in the nucleus of an eukaryotic cell.
Also Read: Genetic Material- DNA vs RNA
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.
Also Read: What is VNTR
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 fibre consisting of the nucleosome.
- Higher-level DNA packaging of the 30 nm fibre into the metaphase chromosome.
Methods used to Analysis Chromatin
Chromatin Immunoprecipitation Sequencing
A process mainly used for analyzing the interactions of the protein with DNA. The binding sites of DNA combined proteins are identified by the Chromatin Immunoprecipitation and parallel DNA sequencing.
Formaldehyde-Assisted Isolation of Regulatory Elements Sequencing
This method is mainly used to control the sequences of those DNA regions of the genome, which are related to the regulatory activity.
DNase I Hypersensitive Sites Sequencing
It is mainly used for recognizing the position of monitoring regions, mainly based on the genome-wide sequencing, which is sensitive to cleavage by DNase I.
Assay for Transposable Accessible Chromatin Sequencing
A technique mainly used for studying the accessibility of chromatin. ATAC-seq is the opposite method of MNase-seq. Tn5 transposase is used for synthetic transposition into the available regions of the genome.
A technique mainly used for identifying the DNA-binding protein:
Micrococcal Nuclease Sequencing
A method mainly used for studying about the nucleosomes by digesting chromatins. This sequence mainly uses micrococcal nuclease enzyme for identifying the position of the nucleosome throughout the genome.
Difference between Chromosome and Chromatin
The table below shows the main differences between the chromatin and chromosome.
|Chromosomes are condensed Chromatin Fibers.||Chromatin is composed of a nucleosomes-a complex of DNA and proteins.|
|Chromosomes are thick, compact and have a ribbon-like shape||Chromatin is a thin and long fibre|
|Distinctly visible during cell division.||Found throughout the cell cycle.|
Explore more: Differences between chromatin and chromosomes
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