Difference between Euchromatin and Heterochromatin

Biology is a diverse subject comprising information regarding different parts of the body. The human body is a mechanism of the respiratory system, digestive system, intestines, etc. All these systems work in a synchronized way to protect the body from diseases and disorders. A person gets ill when these systems do not function properly. Sometimes the disease is self-treatable, but sometimes medication is required. Thus, it is essential to keep the body healthy by eating the right food, doing physical exercises, yoga, meditation, etc.

Today, we will talk about the DNA and proteins present in the cells (chromatin). There are two kinds of chromatin that are present in the human body, i.e., heterochromatin and euchromatin. So, let us begin by understanding their meaning, followed by their differences.

Euchromatin

Euchromatin is defined as the chromosome material that does not accept cell division readily. Euchromatin is helpful in representing major genes and includes transcription. Now, what is transcription? Well, it is the process of synthesizing RNA using the existing DNA or vice-versa. The word 'euchromatin' was first discovered by Walther Flemming. The chromatin structure present in euchromatin is quite loose and active for transcription. Euchromatin is a light form of chromatin, including DNA, RNA, and proteins. It is interesting to note that euchromatin is also known as 'beads on a string.' This is because the euchromatin has a stark resemblance to the necklace.

Now, where is euchromatin located? Well, the euchromatin is located away from the chromosomes. It is in a dispersed form situated around the nucleus. In euchromatin, the nucleosomes are linked with the DNA. Euchromatin is an active form of chromatin that undertakes the process of transcription.

Interestingly, 90-92% of the human genome (cell nucleus) comprises of euchromatin. Euchromatin is a decondensed form of chromatin present in the cell structure. The nucleosomes present in chromatin comprise of eight proteins called histones. Along with that, 147 base pairs of DNA are also present in euchromatin. Euchromatin does not stain quickly as it appears as a light-colored band. In prokaryotic cells, only chromatic is present as the basic form of chromatin. Well, some of the functions of euchromatin are that they help in the initiation of the process of transcription; it controls gene expression, helps in the survival of cells, serves as a direct link to the nucleus, etc.

Heterochromatin

Heterochromatin is defined as the chromosome material having a varied density. In heterochromatin, the genes are either suppressed or modified. Heterochromatin is an inactive part of the genome. Heterochromatin stains darker as compared to euchromatin. One of the major functions of heterochromatin is to avoid genetic instability. Well, it is interesting to note that there are two significant kinds of heterochromatin, i.e., constitutive heterochromatin and facultative heterochromatin. They differ from one another in terms of the DNA they contain. The richness of satellite DNA is essential to determine the nature of heterochromatin. Now, where is heterochromatin located? Well, heterochromatin is a condensed form of chromatin that is found in telomeres and centromeres. Repetitive DNA is present in heterochromatin, and the genes present in them are relatively poor. Heterochromatin is naturally formed by RNA in the nucleus of eukaryotic cells. It silences the gene expressions during the formation. It is interesting to note that heterochromatin is quite smaller than nucleoli. The stain of heterochromatin is dark and blue in color. Another function of heterochromatin is that they regulate gene transcription during the cell cycle.

Now, there are certain differences between heterochromatin and euchromatin. So, let us discuss them in brief.

So, these are some of the contrasting points between euchromatin and heterochromatin. Now, there are certain characteristics associated with euchromatin and heterochromatin. So, let us have a look at them.

Characteristics of Euchromatin

1. Euchromatin is loosely packed DNA.
2. It is lightly stained as compared to heterochromatin.
3. Euchromatin is transcriptionally active.
4. The DNA present is quite less in euchromatin.
5. Euchromatin has a bead-like structure.
6. The nucleosomes present in euchromatin have histone proteins.
7. Euchromatin has only one form, i.e., constitutive euchromatin.
8. When euchromatin is transformed into heterochromatin, it leads to the regulation of gene expression and replication.

Characteristics of Heterochromatin

1. Heterochromatin exists in multiple forms.
2. The genes in chromosomes are inactivated.
3. Heterochromatin is present in the nucleus and also in prokaryotic cells.
4. There are two kinds of heterochromatin, i.e., constitutive heterochromatin and facultative heterochromatin.
5. The Y chromosome in men has large amounts of heterochromatin.
6. The DNA is tightly packed in heterochromatin that prevents the destruction of chromosomes.

So, these are some of the characteristics of euchromatin and heterochromatin. Euchromatin and heterochromatin are present in every organism. Both have certain differences that are listed above. Thus, both euchromatin and heterochromatin are present in all organisms actively and inactively.