Difference Between Euchromatin and Heterochromatin Overview
Chromatin comes in two varieties: euchromatin and heterochromatin. Eukaryotic cells have both euchromatin and heterochromatin, whereas prokaryotic cells only have euchromatin. Euchromatin and heterochromatin have distinct functions in cells. Heterochromatin is characterized as a chromosomal region that is deeply stained with a DNA-specific dye and is relatively condensed. Euchromatin is the region of the chromosome that is densely packed with genes that actively engage in the transcription process.
Difference Between Euchromatin and Heterochromatin Definitions
Euchromatin
It is a kind of chromatin that is loosely packed. During transcription, these are active. It comprises around 90% of the human genome. Housekeeping genes are a kind of euchromatin. Euchromatin is a kind of chromatin that is loosely packed. It is a chromosomal region with a high concentration of genes. During transcription, euchromatin is quite active. Euchromatin has a structure comparable to that of nucleosomes, which comprise histone proteins with around 147 base pairs of DNA wrapped around them. Euchromatin participates actively in the transcription of DNA into RNA. The process by which euchromatin is changed into heterochromatin or vice versa is known as the gene-regulating mechanism. One type of euchromatin is said to be housekeeping DNA.
Heterochromatin
In the nucleus, heterochromatin is a closely packed type of DNA. They are so densely packed that the proteins involved in gene expression cannot access them. There are two kinds of heterochromatin: facultative heterochromatin and constitutive heterochromatin.
Heterochromatin is characterized as a massively stained area of the chromosomes that is relatively condensed with DNA-specific strains. The structure of heterochromatin is so dense that it is difficult to gain access to the proteins involved in gene expression. Because of the aforementioned reasons, performing the chromosomal cross-over becomes challenging. As a result, heterochromatin is both transcriptionally and genetically inert.
Difference Between Euchromatin and Heterochromatin Functions
The following table explains the function of euchromatin and heterochromatin-
|
Euchromatin |
Heterochromatin |
|
Euchromatin is the chromatin involved in the active transcription of DNA into mRNA. |
The functional characteristics of heterochromatin are determined by chromatin alterations. |
|
Transcription can begin because Euchromatin is more open, allowing the recruitment of RNA polymerase complexes and gene regulatory proteins. |
The heterochromatin core histones found in yeast are hypoacetylated, which causes the lysine residues to become more positively charged, allowing for an increase in the interaction between the histone and DNA, resulting in a more closed structure of the nucleosome. |
|
- |
The tight chromatin structure of heterochromatin is owing to the low acetylation of histone H4-K16 in heterochromatin, which promotes folding to high structural orders. |
|
- |
Hypomethylation of heterochromatin at H3-K4 and K79 causes active transcriptional activity. |
Difference Between Euchromatin and Heterochromatin Structure
The following table explains the structure of euchromatin and heterochromatin-
|
Euchromatin |
Heterochromatin |
|
Euchromatin is the more open and active type of chromatin present in the cell's nucleus. |
The structure of heterochromatin is unknown, although it is believed to have a densely packed structure that is difficult to access and transcribe. |
|
This kind of chromatin is uncoiled and contains more DNA and proteins. |
Heterochromatin is commonly located around the chromosome's centromere and is hypothesized to serve a function in chromosomal stability. |
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Euchromatin has a role in the transcription of DNA into RNA, which is the initial step in the gene expression process. |
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Difference Between Euchromatin and Heterochromatin Characteristics
Euchromatin
The characteristics of euchromatin are as follows-
- Euchromatin is DNA that is loosely packed.
- In comparison to heterochromatin, it is just mildly stained.
- Euchromatin participates in transcription.
- Euchromatin has very little DNA.
- The structure of euchromatin is bead-like.
- Histone proteins are found in the nucleosomes of euchromatin.
- Euchromatin exists in just one type, constitutive euchromatin.
- When euchromatin is changed into heterochromatin, gene expression and replication are regulated.
Heterochromatin
The characteristics of heterochromatin are as follows-
- Heterochromatin comes in a variety of types.
- Genes on chromosomes are rendered inactive.
- Heterochromatin may be seen in both the nucleus and prokaryotic cells.
- Heterochromatin is classified into two types: constitutive heterochromatin and facultative heterochromatin.
- The Y chromosome of men has a lot of heterochromatin.
- The DNA is densely packed in heterochromatin, preventing chromosomal disintegration.
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Difference Between Euchromatin and Heterochromatin
The following are the key distinctions between heterochromatin and euchromatin-
|
Parameters |
Euchromatin |
Heterochromatin |
|
Meaning |
It is characterized by less massive staining and DNA sequences that are transcriptionally active or may become transcriptionally active at some point during growth. |
When stained with nuclear stains and transcriptionally inactive sequences, heterochromatin is characterized by firmly packed or condensed DNA with large stains. |
|
Examples |
Except for heterochromatin, all chromosomes in the genome are instances of euchromatin. |
Telomeres and centromeres, one of the X chromosomes, human genes 1, 9, and 16, and Barr bodies are some examples. |
|
Location |
It is located in the nucleus's inner body. |
It is present on the outskirts of the nucleus. |
|
Types |
It is made up of only one type: constitutive euchromatin. |
There are two kinds of heterochromatin: constitutive and facultative. |
|
DNA Form |
To generate a beaded structure, the DNA is compressed and unfurled. |
The histone proteins compress and fold the DNA. |
|
Functions |
It allows for gene transcription and diversity within the genes. |
Heterochromatin keeps the genome structurally intact and enables gene expression control. |
|
Heterozygosis |
Heterozygosis is not indicated by euchromatin. |
Heterochromatin denotes heterozygozygosis. |
|
Replication |
It is early replicative chromatin that replicates before heterochromatin. |
It is a late replicative, replicating after euchromatin. |
|
Staining |
It has been mildly discolored by radioactive stains. |
It is discolored heavily by nuclear stains. |
|
DNA Content |
Euchromatin is made up of less DNA that has been mildly compacted with histone proteins. |
Heterochromatin is made up of more DNA that is densely packed with histone proteins. |
|
Found in |
Both prokaryotes and eukaryotes |
Only eukaryotes |
|
Genetic Process |
It is influenced by a variety of genetic mechanisms. |
Genetic mechanisms have no effect on heterochromatin. |
|
Transcription |
It has transcriptional activity. |
It has no transcriptional activity. |
|
Genes |
The genes discovered here are either now active or will be active throughout development. |
The genes present in this are often dormant. |
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Difference Between Euchromatin and Heterochromatin Key Differences
The following are the key differences between heterochromatin and euchromatin-
- The densely packed form of DNA in the chromosome is known as heterochromatin, whereas the loosely packed form is known as euchromatin.
- Heterochromatin is tightly wound and replicative late, whereas euchromatin is loosely wound and replicative early.
- The density of DNA in heterochromatin is high and stained darkly, whereas the density of DNA in euchromatin is low and colored softly.
- Heterochromatin regions are sticky, whereas euchromatin regions are not.
- The phenotypic of an organism stays unaltered in the Heterochromatin section, while variation may be detected owing to the influence of DNA throughout the genetic process in the Euchromatin.
- Heterochromatin provides for gene expression control and also protects cell structural integrity, whereas Euchromatin causes genetic variances and allows for genetic transcription.
- Heterochromatin is exclusively present on the perimeter of the nucleus in eukaryotic cells, whereas euchromatin is found in the inner body of the nucleus in both prokaryotic and eukaryotic cells.
- Heterochromatin has little or no transcriptional activity and is genetically inactive; on the other hand, Euchromatin actively participates in the transcription process and is genetically active.
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Points to Remember
- The chromosome in the cell is made up of genetic material called chromatin, which is composed of DNA, RNA, and proteins. It is classified into two types: euchromatin and heterochromatin.
- In 1880, Walther Flemming discovered chromatin. He termed the bundle of fibers present in the cell nucleus "chromatin."
- Euchromatin is loosely packed chromatin with little nucleus staining, whereas heterochromatin is firmly packed chromatin with a lot of nucleus staining.
- Euchromatin occupies more than 92% of the genome, while heterochromatin occupies less than 10% of the genome.
- Euchromatin is found in the nucleus's inner body, whereas heterochromatin is found on the nucleus's periphery.
- In genetics investigations, heterochromatin is found more frequently than euchromatin. This is due to heterochromatin's dense structure.
- Euchromatin can be found in both eukaryotes and prokaryotes; however, heterochromatin can only be found in prokaryotes.
- Euchromatin has a bead and string-like structure, but heterochromatin has two types: line and satellite.
- Euchromatin facilitates DNA transcription into mRNA, whereas heterochromatin prevents DNA transcription.
Sample Questions for Difference Between Euchromatin and Heterochromatin
Sample Question 1: Where do euchromatin and heterochromatin reside?
Ans. Both chromatins are found within the chromosomes; however, euchromatin is found within the nucleus's inner body, while heterochromatin is found around the nucleus's perimeter.
Sample Question 2: Is it possible for male X chromosomes to become inactive?
Ans. Male X chromosome inactivation is common, although it is temporary and limited to the last stage of spermatogenesis.
Sample Question 3: What transcriptional products does RNA polymerase III produce?
Ans. RNA polymerase III is responsible for the transcription of tRNA, 55 rRNA, and snRNAs (small nuclear RNAs).
Sample Question 4: How does euchromatin enable DNA transcription?
Ans. The unfolded shape of nucleosomes and the DNA string in euchromatin allows gene regulatory proteins and RNA to interact with the segment of DNA, resulting in DNA transcription.
Sample Question 5: Distinguish between capping and tailing.
Ans. Capping involves the addition of an uncommon nucleotide to the 5′ ends of hnRNA. In tailing, 200-300 adenylate residues are inserted independently at the 3′ ends of a template. It is also known as mRNA.
Sample Question 6: What commonalities do euchromatin and heterochromatin share?
Ans. Euchromatin and heterochromatin both include DNA, RNA, and proteins, as well as nucleosomes and DNA strands. The packed density of nucleosomes is what distinguishes them.
Sample Question 7: What transcriptional products increase mRNA length?
Ans. mRNA is a kind of nuclear RNA. It contains information on the genes that create proteins. mRNA is also known as messenger RNA.