CpG Sites

CpG sites are specific regions in DNA where a cytosine nucleotide is followed by a guanine nucleotide, linked by a phosphate bond. These sites are important because they often act as "on/off" switches for gene activity through a process called DNA methylation—adding a methyl group to the cytosine. This modification can regulate gene expression without changing the underlying DNA sequence, influencing various biological processes and disease states. Essentially, CpG sites are key regulatory elements, helping control how and when genes are turned on or off in our cells.