Final answer:
DNA methylation is an epigenetic mechanism that suppresses transcription by adding methyl groups to DNA, leading to gene inactivation. It plays a role in development, heredity, and disease, and is targeted by drugs to treat cancer.
Step-by-step explanation:
DNA methylation is a mechanism used by eukaryotes to inactivate genes. This form of epigenetic modification involves the addition of methyl groups to certain cytosine nucleotides within the DNA, particularly in regions called CpG islands commonly found in gene promoter areas. Once methylated, these genes typically become silenced, meaning they are not expressed or transcribed into RNA. This modification can be passed through cell divisions, making some epigenetic changes heritable, and plays a crucial role in regulating gene expression, embryonic development, and has implications in diseases like cancer. Moreover, environmental factors can affect DNA methylation patterns, thereby modifying gene expression.
New drugs are being developed that target the methylation patterns of DNA and histone modifications. By decreasing DNA methylation and inhibiting the removal of acetyl groups from histone proteins, these drugs can reactivate genes that help kill tumor cells by inducing apoptosis or halting their proliferation. Understanding the gene expression patterns in cancer cells can help identify which genes are being abnormally expressed or silenced, leading to the development of targeted therapies.