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What is DNA Methylation ?
What is DNA methylation? This is a question asked by many people who are looking for answers regarding the role of nutrition and aging in relation to health. DNA methylation is an ancient biochemical process by which different methyl groups are inserted into the DNA double helix. methylation can either change the activity of an individual DNA sequence or affect the promoter site. For instance, when located on the genetic promoter, methylation usually acts to inhibit gene expression.
DNA methylation is transfer of methyl group from SAM to Adenine or Cytosine. Therefore, this addition takes place on two DNA bases which are at Adenine and Cytosine.
DNA methylation is known as covalent modification which means it does not change sequence of DNA but affects the gene activity.
Thus is done by enzyme DNA methyltransferses or called as DNMTs
These DNMTs are of three types:
1. DNMT1
2. DNMT 3a
3. DNMT 3b
DNMT1 is used in maintenance of DNA methylation within the cell. It means it maintains the methylation from parent DNA strand to newly synthesised strand. DNMT 3a and DNMT 3b are required for de Novo methylation. They do not need hemi-methylated DNA, thus methyl groups added to new positions.
Molecular basis of DNA methylation
The molecular basis of DNA methylation is established from the results of certain experiments that were carried out using laboratory animals. The results showed that the cytosine content at the promoters of several genes, including the genes that control sexuality in mammals, was increased after exposure to an acidic environment. Surprisingly, exposure to an alkaline condition resulted in the same results, but with the addition of DNA methylation at the promoters, this cytosine-demethylase was found to be non-functional, suggesting that it was responsible for the increased levels of cytosine at these locations.
How does DNA methylation affect genes?
It has been found that promoters of genes can be affected by DNA methylation, especially when these genes are active.
When methyl groups are present in the DNA sequence, other molecules called substrates move around the DNA and attach to them. These substrates can then regulate the gene expression in a number of ways. For example, when the methyl groups at the promoters of a specific gene are affected, it will make it more difficult for the gene to become activated. However, if this same promoter region is deleted from the DNA, the promoter will still be active and this process will continue.
DNA Methylation in nature
There are many different examples of DNA methylation reactions that take place in nature. For example, DNA methylation of the cytosine in DNA is used in the generation of sperm. As the DNA sequence is passed down the generations, the number of repeats increases as it becomes more common. In this way, many different genes are being generated within a single gamete. Interestingly, we can see this happening as the result of a number of different biological processes.
Another example of DNA methylation patterns is the way that the promoter of an imprinted locus is expressed during development. During development, various combinations of genetic instructions are being produced. Interestingly, there are times when multiple sets of these instructions are activated in the same area of the genome at the same time, which results in an imprinted locus. We call this a locus.
When we study how methylomes affect the DNA, we need to think of it in terms of a map. Think of this as the borders of a country. In the case of DNA, the methyl groups act like the walls that separate one region from another. methylation, or the switching of a methyl group is typically found in the promoter region of genes, and there are many different sets of promoters throughout the genome. This is basically what happens when a person gives birth to a child.
The concept of what is DNA methylation can be very complicated, but we need to simplify it first. DNA is the blueprint of life. It is also called DNA because it is identical to DNA, the genetic material that makes everything in the world to grow and function correctly. Because DNA is heritable, changes to the genetic material can only occur between the gametes. So, methyl groups, which are combinations of two DNA letters, can switch between regions of the genome.
What is DNA methylation used for in cellular processes?
During gamete pairing, the DNA letters are switched by methyl groups, creating different patterns that dictate specific traits that can be passed down through generations. Methylated sperm, and methylated egg cells, do not always behave the same way, and these traits can be influenced by methylation. Research has shown that specific types of mice and rats can be made to behave in certain ways depending on the presence of methyl groups. These results demonstrate the importance of understanding the relationship between methylation and cell differentiation.
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