Epigenetics is the study of heritable changes in gene expression that occur without changes in DNA sequence. The main epigenetic mechanisms are DNA methylation, histone modification, and non-coding RNA. DNA methylation involves adding methyl groups to DNA, typically to adenine and cytosine bases, and results in gene silencing, transposon control, X chromosome inactivation, genomic imprinting, and tissue-specific gene expression.

2. Study of heritable changes in gene expression that occur
without any changes in DNA sequence.
The best understood epigenetic mechanisms are:
1- DNA Methylation
2- Histone modification
3- Non coding RNA
DNA methylation = INACTIVATES DNA transcription..

3. • is a biological process by which methyl groups (-CH3) are added to the DNA
molecule.
DNA methylation takes place: adenine and cytosine.
• Gene silencing (Transcriptional silencing).
• Transposon control (silencing).
• X chromosome inactivation.
• Genomic imprinting.
• Tissue specific gene expression.

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