The portion of the chromosome that is deeply stained with a DNA-specific dye and is in a comparably condensed form is known as heterochromatin. On the other hand, Euchromatin is a region of the chromosome that is densely packed with genes and actively participates in the transcription process. So, what is the difference between euchromatin vs heterochromatin?
Well, understanding the differences between heterochromatin and euchromatin is crucial in biology. Furthermore, the DNA in heterochromatin is condensed or closely bonded. Euchromatin’s DNA, on the contrary, is compressed or weakly bound. Keep on scrolling down, and we will find out all the differences between euchromatin vs heterochromatin.
What Is Euchromatin?
Before we tell you the differences between euchromatin vs heterochromatin, let us tell you that euchromatin is a kind of chromatin that has a light packing pattern. Additionally, the presence of euchromatin usually invariably indicates that cells are transcriptionally active. This shows that they are actively transcribing DNA to mRNA.
Euchromatin Structure:
The majority of the initial gene exons in euchromatin are unmethylated. They can be found in the distal arms of the chromosome in decondensed form. Euchromatin is distributed throughout the nucleus and duplicated throughout the S Phase.
The transcriptionally active version of chromatin is called the euchromatin. With the presence of beads on a string, euchromatin has a less compact structure and is commonly referred to as 11 nm fiber. Nucleosomes are represented by the beads, while DNA is represented by the string.
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Euchromatin Function:
Euchromatin is the chromatin that is involved in the active transcription of DNA into mRNA. Transcription can begin because euchromatin is more open to facilitating the recruitment of RNA polymerase complexes and gene regulatory proteins.
What Is Heterochromatin?
Heterochromatin is a kind of chromatin that has a dense packing pattern. Furthermore, this is the primary distinction between euchromatin vs heterochromatin, as the latter is distinguished by light packing. It also prevents RNA and DNA polymerases from finding their way into DNA.
Heterochromatin Structure:
It has a compact and densely packed structure. Modifications to histones and the expansion of silencing complexes produce changes in chromatin design, resulting in heterochromatin. Heterochromatin does not fully express its genes due to its repressive nature.
Heterochromatin frequently folds into higher-order structures, causing negative supercoiling of DNA to rise. As a result, Heterochromatin’s design is both stable and dynamic, changing with the cell cycle. But, the DNA elements that encourage the creation of active chromatin and remove nucleosomes aid in chromatin formation. This makes it possible for heterochromatin to spread.
Heterochromatin Types:
By examining the ‘Constitutive Heterochromatin’ and ‘Facultative Heterochromatin,’ the structure of Heterochromatin may be clearly understood. Constitutive Heterochromatin is a persistent kind of heterochromatin made up of repeating DNA sequences known as Satellite DNA. This heterochromatin is found in centromeres and telomeres and regulates structural functions.
Facultative Heterochromatin is known to alter over the cell cycle. This is made up of ‘LINE Sequences,’ which are repeating DNA sequences. The structure of the inactivated X-chromosome in females changes as a resultant factor. The density gradient data may also be used to identify heterochromatin structures.
It shows that heterochromatin has a stable structure while euchromatin has a distinctive design, which makes up the primary difference between euchromatin and heterochromatin. They have several more differences in terms of DNA density, nucleus stain, location, genetic impact, transcriptions, genetic formation, replication, heteropycnosis, etc.
Heterochromatin Function:
Modifications to chromatin dictate the functional characteristics of heterochromatin. For example, in yeast, the heterochromatin core histones are hypoacetylated, causing the lysine residues to become more positively charged.
It allows for more significant contact between the histone and DNA, resulting in a more closed nucleosome shape.
As heterochromatin has low acetylation of Histone H4-K16, it has a tight chromatin structure, which promotes chromatin folding to higher structural orders. In addition, the hypomethylation of heterochromatin at H3-K4 and K79 results in active transcriptional activity.
Euchromatin Vs Heterochromatin- The Differences
Euchromatin vs Heterochromatin differences is distinctively clear because we know one is the uncoiled, and tightly packed form of chromatin, while the other is a lightly packed form of it. We’ve listed the differences between Euchromatin vs Heterochromatin to help you understand how they vary.
| Category | Euchromatin | Heterochromatin |
| DNA Conformation | It is unfolded and compressed, giving birth to a beaded structure. | It is folded and condensed with histone protein. |
| Transcription | It is transcriptionally active. | It is transcriptionally inactive. |
| Stain | It is lightly stained. | It is darkly stained. |
| Genes | The genes found here are active or will be active soon. | The genes found here are inactive. |
| DNA Content | It is made with less amount of lightly compressed DNA. | It is made with more amount of tightly compressed DNA. |
| Genome Content | It forms almost 90%-92% of the genome. | It forms almost 8%-10% part of the genome. |
| Regions | Euchromatin has non-sticky regions. | Heterochromatin has sticky regions. |
| Location | It is found in the innermost part of the nucleus and is present in both and eukaryotes and prokaryotes. | It is found in the periphery of the nucleus and is found only in the eukaryotes. |
| Function | Euchromatin allows variation and transcription of the gene. | Heterochromatin allows gene expression and maintains the genome’s structural integrity. |
| Heteropycnosis | It does not exhibit heteropycnosis. | It exhibits heteropycnosis. |
| Replication | It replicates earlier than heterochromatin. | It replicates later than euchromatin. |
| Types | It has only one type, which is constitutive euchromatin. | It has two types such as facultative and constitutive heterochromatin. |
| Transcriptional Activity | It exhibits low transcriptional activity. | It exhibits high transcriptional activity. |
| Genetic Impact | It is not impacted by various generic procedures. | It is impacted by genetic procedures. |
Putting It All Together
We have already described the differences between euchromatin vs heterochromatin here. We have also defined euchromatin and heterochromatin, including their functions, structural composition, and types. If you study this article thoroughly, it will certainly clear up your confusion about these DNA compositions. You can also share your questions with us in the comment box below if you have any, and we will get back to you with an answer.
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