Heterochromatin vs Euchromatin
Although these are minute structures, the function of chromatin is extremely important to shelter the information that codes for the traits of organisms. Chromatin is the structure that holds the DNA strand of a chromosome. Heterochromatin and euchromatin are the two main types of chromatin that are present in the cells. The structure and function are different between these two types. In addition, the transcription and replication properties are varied between heterochromatin and euchromatin.
Heterochromatin is the tightly packed chromatin in the cells of eukaryotes and those have been usually found at the periphery of the nucleus. Since heterochromatin is tightly packed, it could be easily observed when the DNA is stained. This intensely stained DNA is of two types known as constitutive and facultative. Constitutive heterochromatin is basically responsible for forming of the centromere or the telomere while attracting signals for both gene expression and repression. Facultative heterochromatin becomes repetitive under special signals or environments; otherwise it stays quiet with a highly condensed structure. Basic function of heterochromatin is to shelter the DNA strand, but the regulation of genes is also accomplished from chromatin. When there is a DNA strand without heterochromatin, the cell cycle and all other processes are obstacle unless the endonuclease enzymes would digest the strand. Therefore, the presence of heterochromatin means a lot for a cell and any organism.
The presence of heterochromatin in the next generation is ensured through inheritance. Usually, the condensed structure ensures the genes are not always expressed unless a special signal arrives and uncondensed to expose the DNA strand for transcription mRNA. When the replication of DNA in heterochromatin is considered, usually it takes place in the latter stages. Its compact structure determines most of the functions in gene expression; in fact, it is sometimes called the gene silencing.
Euchromatin is the loosely packed DNA sheltering structures in the cells, and those are usually found towards the inner core of the nucleus. Euchromatin is present in both prokaryotes and eukaryotes. In fact, euchromatin is the only type of chromatin present in the prokaryotic genetic material. Therefore, it could be envisaged that it was euchromatin that happened to be in organisms before others did. Its loosely packed structure causes less visibility when the DNA is stained. The uncondensed nature happens to be present due to the loose wrapping of histone proteins around the DNA strand. Therefore, the access of DNA is easy to initiate the DNA transcription. One of the main interests about euchromatin is that it contains the mostly active genes of an organism. That is because euchromatin participates actively in the transcription of DNA into mRNA. Some of the euchromatins are not always transcribed but transformed into heterochromatin after the basic function to silence the genes. However, there are some ever active euchromatins to maintain the stability of the basic and essential processes for the survival of the cell.
What is the difference between Heterochromatin and Euchromatin?
• Euchromatin is loosely packed DNA while heterochromatin is densely packed.
• Euchromatin is present in both prokaryotes and eukaryotes while heterochromatin is only present in eukaryotes. That means euchromatin happened to be in organisms before heterochromatin did.
• Heterochromatin is of two types, but euchromatin is present in only one form.
• Heterochromatin is easily and highly stained but not euchromatin.
• Euchromatin is highly active but heterochromatin is not.
• Heterochromatin is found at the periphery of the nucleus while euchromatin is present in the inner body of the nucleus.