Difference between Euchromatin and Heterochromatin

Before differentiating between euchromatin and heterochromatin, one must understand what chromatin is. During the interphase, it is an essential component inside the cell nucleus made of DNA and histone proteins. Chromatin packs the DNA into small volumes to adjust in the cell, strengthening it for mitosis and meiosis. The entire chromatin structure is either euchromatin or heterochromatin, helping in replication gene expression and saving DNA from damage.

Although both are chromatin types, their dissimilarities make them significant. Now, if you wonder what do heterochromatin and euchromatin do, we have a complete article written on it below! However, euchromatin is the active chromatin inside the nucleus, whereas heterochromatin is the inactive form of chromatin. Let’s discuss the differences between euchromatin and heterochromatin in detail.

Comparison Table

Factor	Euchromatin	Heterochromatin
Presence	Eukaryotes and prokaryotes	Eukaryotes
Location	Centre of the cell	Cell’s periphery
Structure	Beaded structure	Compact structure
Function	Transcription, and gene variation	Genome structure, and gene regulation
Genetic Process influence	Yes	No
Genome content	90% in humans	8-10% in humans
Stickiness	No such regions	Sticky
Staining	Lightly stained	Dark stained
Examples	Most chromosomes	Genes 1, 9, 16

What is Chromatin?

As mentioned earlier, chromatin is the genetic material inside the nucleus, made of DNA and proteins. DNA carries genetic information, while proteins help bind the genetic material into a compact form to fit in the nucleus. Chromatin is the unwound form of chromosomes that packages to create chromosomes at the time of division. A complete chromatin body is divided into euchromatin and heterochromatin.

Let’s continue to know about euchromatin vs heterochromatin.

What is Euchromatin?

According to the name Euchromatin, the “true chromatin” is loosely packed and actively involved in transcription to produce mRNA. The structure of euchromatin and nucleosomes is alike, with 147 DNA base pairs wrapped around the histone proteins. The loosely bound DNA enables quick transcription due to its immediate availability. The gene-regulating mechanism makes it possible to transform heterochromatin into euchromatin and vice versa. Euchromatin is involved in transcription using active genes and helps encode functional proteins. Euchromatin is said to contain 90% of the total human genome

What is Heterochromatin?

Now, the subsequent question coming to your mind must be how is euchromatin different from heterochromatin? Although both replicate at different times, heterochromatin is the highly compact and dense chromatin, preventing RNA and DNA polymerase and other proteins from finding their way to the DNA. Heterochromatin is only present in the nucleus of eukaryotes to help in replication. It is of two types, facultative and constitutive heterochromatin. The facultative heterochromosomes are inactive genes and are not a permanent feature of all cell nuclei. They form through the process of siRNA or histone methylation. Alternatively, constitutive heterochromatin makes the repetitive, functional genes like centromeres and telomeres. They are the continuing nature of the nucleus and retain their structure during the interphase of cell division.

Similarities between Euchromatin and Heterochromatin

Besides the euchromatin and heterochromatin differences, these will remain the types of chromatins; thus, they have some common points. These are explained below:

• Both are the DNA sequences formed of polynucleotide chains but with different functions.
• Besides, both are assembled via primary nucleosome assembly.
• Moreover, these types of chromatins are prominent during the interphase stage of cell division.
• Euchromatin and heterochromatin have special features to interact with a specific type of protein called histone protein. These protein structures help in chromosome packaging.

Euchromatin vs Heterochromatin – Primary Differences

Definition

Euchromatin

Euchromatin is the loosely packed form of DNA containing different segments of genes in the nucleus and transcription.

Heterochromatin

On the other hand, heterochromatin is tightly packed DNA present in the nucleus and is transcriptionally inactive.

Presence

Euchromatin

The loose part of chromatin, i.e., euchromatin, is found in the nucleus of both prokaryotes and eukaryotes.

Heterochromatin

Unlike euchromatin, you can observe heterochromatin only in eukaryotic organisms through a microscope.

Location

Euchromatin

You will observe euchromatin widely distributed in the center or inner body of the nucleus.

Heterochromatin

Whereas, when going through euchromatin vs heterochromatin, the latter is more prominent along the periphery of the cell nucleus.

Structure

Euchromatin

The DNA of euchromatin forms a loose beaded structure within the nucleus to fit well.

Heterochromatin

However, the DNA of a heterochromatin is wrapped around a structural protein called histone protein to form a compact structure.

Function

Euchromatin

Euchromatin is entirely different from heterochromatin when it comes to functions. It enables the process of transcription and gene variation occurring within the genes.

Heterochromatin

In contrast, heterochromatin is responsible for maintaining the structure of the genome and gene expression regulation.

Activity

Euchromatin

Euchromatin is transcriptionally active and involved in transcription that further helps maintain the chromosomal organization and cellular functions.

Heterochromatin

Contrary to euchromatin, heterochromatin is not involved in transcription and is transcriptionally inactive.

Genetic Process Influence

Euchromatin

There is a substantial genetic influence on the chromatin types. For example, euchromatin is affected by numerous genetic processes like position-effect variegation.

Heterochromatin

Discussing the other type of chromatin, i.e., heterochromatin, is not even slightly affected by the genetic processes.

Genome Content

Euchromatin

Euchromatin comprises most of the human genome, comprising around 90% of the total.

Heterochromatin

Whereas heterochromatin makes a smaller part of the genome, making around 8 – 10% of the human genome.

Stickiness

Euchromatin

In the euchromatin vs. heterochromatin race, the former does not have sticky regions in the structure.

Heterochromatin

Alternatively, heterochromatin has some sticky regions to help chromatin make its place inside the nucleus.

Staining

Euchromatin

Euchromatin appears as the lightly stained type of chromatin.

Heterochromatin

When observed under a microscope, heterochromatin appears to be darkly stained.

Examples

Euchromatin

All types of chromosomes in a genome are examples of euchromatin besides heterochromatin.

Heterochromatin

Some of the heterochromatin present in the genome are genes 1, 9, and 16.

The Bottom Line

Heterochromatin and euchromatin are both types of chromatin and essential parts of the cell. When discussing euchromatin vs heterochromatin, both are different and have specific roles. The euchromatin is directly involved in transcription, while heterochromatin maintains the genome structure. There must be numerous differences between the two, but heterochromatin contributes to 10% of the genome in eukaryotes. In short, euchromatin and heterochromatin are crucial in stabilizing gene regulation and balancing the human genome.

FAQs

How does the euchromatin look under a microscope?

You cannot see hetero and euchromatin distinctly under a student microscope. However, one can easily observe it under a compound or electron microscope. Heterochromatin is darkly stained, loosely packed chromatin, while euchromatin is comparatively stained as light pink.

What does the chromatin turn into?

Chromatin folds into specific formations called chromosomes having DNA strands and proteins. They contain the genetic material of the cell and are involved in cell division.

How much chromatin does each chromosome have?

Each chromatin forms one chromosome, which means that every chromosome has one chromatin.

What are the components of chromatin?

Chromatin is primarily made of histone proteins, DNA and RNA. Sometimes, students wonder if it contains lipids; no, lipids are not a component of chromatin.

Is chromatin present in bacteria?

Chromatin is not present in bacteria in the same shape as eukaryotes. However, it forms a membrane-free region commonly known as the nucleoid that modifies shape according to the bacterial state.