DNA METHYLATION
DNA METHYLATION:
There are several types of modification system and processes available for gene
expression; methylation is one of them. Because it regulates the expression of gene.
So the DNA methylation can be defined as;
“ The addition of a methyl group or a chemical cap to the part of DNA molecule,
which prevents certain genes from being expressed. It’s a type of epigenetic
modification”.
SOURCE OF METHYL GROUPS:
From the food this methyl group can come. One example of that food is the dietary
sources.
ENZYME INVOLVED IN METHYLATION:
Eukaryotic DNA methylation occurs through an enzyme called as the DNA
methyltransferase written as DNMT which binds a methyl group to the number 5
position of the cytosine base, forming 5-methylcytosine.
EXAMPLE OF METHYLATION:
Here we have a DNA. In this case we are having a methyl group. The methyl group
will be donated to a particular position because there is a specific site for the
methylation. In this case let’s say the 5 Carbon is the perfect site for the methylation
so this methyl group will be added to this 5 C position onto the cytosine base in the
DNA.
After this transfer of CH3 onto the 5 Carbon position, it will be termed as 5-
methylcytosine.
1
, DNA METHYLATION SITES:
These are very specific sites called as the CpG islands (C for cytosine, p for
phosphate and then Guanine). Repeated sequences of CGCG. The regions found in
our genome consisting of more CpG repeats are called as the gene hotspots. Because
these are the regions for active methylation. Now as the methylation can go on all
the time in these regions there is a tendency of modifying the gene expression from
these sequences in our genome.
2
DNA METHYLATION:
There are several types of modification system and processes available for gene
expression; methylation is one of them. Because it regulates the expression of gene.
So the DNA methylation can be defined as;
“ The addition of a methyl group or a chemical cap to the part of DNA molecule,
which prevents certain genes from being expressed. It’s a type of epigenetic
modification”.
SOURCE OF METHYL GROUPS:
From the food this methyl group can come. One example of that food is the dietary
sources.
ENZYME INVOLVED IN METHYLATION:
Eukaryotic DNA methylation occurs through an enzyme called as the DNA
methyltransferase written as DNMT which binds a methyl group to the number 5
position of the cytosine base, forming 5-methylcytosine.
EXAMPLE OF METHYLATION:
Here we have a DNA. In this case we are having a methyl group. The methyl group
will be donated to a particular position because there is a specific site for the
methylation. In this case let’s say the 5 Carbon is the perfect site for the methylation
so this methyl group will be added to this 5 C position onto the cytosine base in the
DNA.
After this transfer of CH3 onto the 5 Carbon position, it will be termed as 5-
methylcytosine.
1
, DNA METHYLATION SITES:
These are very specific sites called as the CpG islands (C for cytosine, p for
phosphate and then Guanine). Repeated sequences of CGCG. The regions found in
our genome consisting of more CpG repeats are called as the gene hotspots. Because
these are the regions for active methylation. Now as the methylation can go on all
the time in these regions there is a tendency of modifying the gene expression from
these sequences in our genome.
2
