DNAmetilációt

DNAmetilációt is the process by which a methyl group is added to a DNA molecule. This chemical modification typically occurs at a cytosine base, specifically in the context of a CpG dinucleotide. CpG sites are regions where a cytosine is followed by a guanine. While CpG sites are relatively rare in the genome, they are often clustered in regions called CpG islands, which are frequently located in or near gene promoter regions.

DNA methylation is a crucial epigenetic mechanism, meaning it can alter gene expression without changing the underlying DNA sequence. The addition of a methyl group generally leads to gene silencing. This occurs because the methyl group can physically hinder the binding of transcription factors to the DNA, or it can recruit proteins that condense the chromatin structure, making the DNA less accessible for transcription.

This process plays a vital role in a variety of biological functions. It is essential for normal development, including cell differentiation and embryonic development. DNA methylation also plays a role in X-chromosome inactivation in females and genomic imprinting, where only one copy of a gene is expressed. Furthermore, it is involved in the regulation of gene expression throughout an organism's life and contributes to maintaining genomic stability. Aberrant DNA methylation patterns are associated with various diseases, including cancer, neurological disorders, and autoimmune diseases. The study of DNA methylation is a key area of epigenetic research.