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Euchromatin vs. Heterochromatin

Euchromatin is the loosely packed DNA found in the inner body of nucleus and consists of transcriptionally active regions of DNA while heterochromatin is the tightly packed DNA discovered in the periphery of nucleus and consists of transcriptionally inactive DNA regions in the genome.

Key Differences

Euchromatin has low DNA density while heterochromatin has high density.
DNA of euchromatin is affected by genetic processes and variations in alleles while in heterochromatin, the phenotype of an organism remains unchanged.
Harlon Moss
Nov 09, 2017
Euchromatin is lightly stained while heterochromatin stained dark.
Euchromatin regions are not sticky while heterochromatin regions are sticky.
Aimie Carlson
Nov 09, 2017
Condensation and decondensation of DNA are interchanged during the periods of the cell cycle in euchromatin while heterochromatin remains condensed during each period of the cell except DNA replication.
Euchromatin does not show heteropycnosis while heterochromatin shows heteropycnosis.

Comparison Chart


Uncoiled form of chromatin
Tightly packed part of chromosome

Cell Type

Eukaryotic and prokaryotic cells
Eukaryotic cells


Inner part of the body
Peripheral part of the body

Genetically activation

Samantha Walker
Nov 09, 2017


Early replicative
Late replicative
Harlon Moss
Nov 09, 2017


Uniform type
Constitutive and facultative heterochromatin


Genetic transcription and genetic variations
Maintenance of structural integrity and regulation of gene expression.
Harlon Moss
Nov 09, 2017

Euchromatin and Heterochromatin Definitions


Chromosomal material that is genetically active and stains lightly with basic dyes.


Tightly coiled chromosomal material that stains deeply during interphase and is believed to be genetically inactive.


(genetics) uncoiled dispersed threads of chromosomal material that occurs during interphase; it stains lightly with basic dyes


(cytology) Heterochromatic tightly coiled chromosome material; believed to be genetically inactive

What is Euchromatin?

The human body is composed of billions of cells. A typical cell consists of a nucleus and nucleus has chromatin. According to biochemist scientist, the operational definition of chromatin is the DNA, RNA, and protein extracted from eukaryotic lysed interphase nuclei. The loosely packed form of chromatin is called euchromatin. DNA exists in the chromatin form after cell division and becomes loosely packed. Condensation of DNA with histone proteins makes chromatin which exhibits beads on a string like structure. Euchromatin has transcriptionally active sites of the genetic material. Genomic parts which have active genes are loosely packed and allows the transcription of these genes occurs. The frequency of chromosomal crossing over is more in euchromatin and allowing the chromatin DNA to be genetically active. Euchromatin parts in the genome can be observed under the microscope as loops which seem to have 40 to 100 kb regions of DNA in it. Under microscope staining, euchromatin shows light colored bands. The diameter of the chromatin fiber is about 30 nm in euchromatin. Matrix associated regions which have AT-rich DNA are attached to euchromatin loops into the matrix of the nucleus. Euchromatin presence can be seen both in eukaryotic and prokaryotic cells.

What is Heterochromatin?

The tightly packed form of DNA in the nucleus is called heterochromatin. But it is less compact than metaphase DNA. Staining and observation under a light microscope of nondividing cells in the nucleus show two distinct regions which depend on the intensity of the staining. The lightly stained region is called as euchromatin while the dark area is known as heterochromatin. Organization of heterochromatin is more compact in such a way that their DNA is inaccessible to the proteins which are involved in the gene expression. Chromosomal crossing over is avoided by the compact nature of heterochromatin. So, it is considered as transcriptionally and genetically inactive. Functions of the heterochromatin are gene expression and protection of chromosomal integrity. These functions are possible because of dense DNA packing. It is inherited when two daughter cells are divided from a single parent cell, which means newly cloned heterochromatin has same DNA regions which result in epigenetic inheritance. There may be the occurrence of expression of transcribable materials due to the boundary domains. This may lead to the development of different levels of gene expression. Two types of heterochromatin can be identified in the nucleus matric. One is known as constitutive heterochromatin while other is facultative heterochromatin. Constitutive heterochromatin consists of no genes in the genome so it can be retained in its compact structure also during the interphase of the cell. It is a permanent structure of the nucleus of the cell. DNA in the telemetric and centromeric regions belong to the constitutive heterochromatin. Some parts of the chromosomes belong to the constitutive heterochromatin. For example, most of the parts of Y chromosome is a case of constitutional heterochromatin. Facultative heterochromatin has inactive genes in the genome, so it is not a permanent feature of the cell’s nucleus. It can be seen in the nucleus some of the time. Inactive genes of this part may be inactive in some cells or during some periods. When those genes are inactive, they make facultative heterochromatin. Chromatin structures is in the form of beads on a string, 30 nm fiber, active chromosomes in the interphase.

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