1. DNA Methylation

2. DNA methylation, the addition of methyl groups to certain bases in DNA, is associated with reduced transcription in some species DNA methylation can cause long-term inactivation of genes in cellular differentiation In genomic imprinting, methylation regulates expression of either the maternal or paternal alleles of certain genes at the start of development

3. What is Genomic Imprinting? Genomic imprinting is the epigenetic phenomenon by which certain genes are expressed in a parent-of- origin-specific manner.epigeneticgenesexpressed If the allele inherited from the father is imprinted, it is thereby silenced, and only the allele from the mother is expressed.allele If the allele from the mother is imprinted, then only the allele from the father is expressed. Forms of genomic imprinting have been demonstrated in fungi, plants and animals. [1] Genomic imprinting is a fairly rare phenomenon in mammals; most genes are not imprinted. [1]

4. What is EPIGENESIS (epigenetic)? Epigenetics is the study, in the field of genetics, of cellular and physiological phenotypic trait variations that are caused by external or environmental factors that switch genes on and off and affect how cells read genes instead of being caused by changes in the DNA sequence geneticscellularphysiological phenotypic traitenvironmental genesDNA

5. Two of DNA's four nucleotides, cytosine and adenine, can be methylated. Adenine methylation is restricted to prokaryotesnucleotidescytosine adenine

6. Two of DNA's four nucleotides, cytosine and adenine, can be methylated. Adenine methylation is restricted to prokaryotesnucleotidescytosine adenine

7. Methylation modifications that regulate gene expression are usually heritable through mitotic cell division; some methylation is also heritable through the specialized meiotic cell division that creates egg and sperm cells, resulting in genomic imprintingheritable mitotic cell divisionmeiotic cell divisiongenomic imprinting

8. DNA methylation also forms the basis of chromatin structure, which enables a single cell to grow into multiple organs or perform multiple functions chromatin

9. DNA methylation also plays a crucial role in the development of nearly all types of cancer. [4] cancer [4]