33. The pattern of genomic imprinting is maintained from one generation to another by
(1) Phosphorylation of DNA
(2) Methylation of DNA
(3) Acetylation of DNA
(4) Glycosylation of DNA

Genomic imprinting is an epigenetic phenomenon where certain genes are expressed in a parent-of-origin specific manner, meaning only one allele from either the mother or father is active. The pattern of genomic imprinting is maintained across generations primarily by DNA methylation, which is an epigenetic modification involving the addition of methyl groups to DNA. This article explains the process and explores other DNA modifications related to imprinting.

DNA Methylation and Imprinting Maintenance

DNA methylation is the covalent addition of a methyl group, usually to the 5th carbon of cytosine bases in CpG dinucleotides. This methylation acts as a stable epigenetic mark that silences gene expression on one parental allele while leaving the other active. The methylation patterns are established in the germline during gamete formation and are maintained through somatic cell divisions by maintenance methyltransferases like DNMT1. This ensures the imprinting pattern is faithfully transmitted from parents to offspring, preserving gene expression differences based on parental origin. Loss of this methylation would cause loss of imprinting, which can lead to diseases and developmental disorders.​

Explanation of Other Options

• Phosphorylation of DNA: This involves adding a phosphate group, mostly related to DNA repair and replication, not imprinting maintenance. It does not function as a stable epigenetic mark for imprinting.​

• Acetylation of DNA: DNA acetylation is not a common modification; however, acetylation mainly affects histones (histone acetylation), influencing chromatin structure and gene expression indirectly. It is not the primary mechanism maintaining genomic imprinting.​

• Glycosylation of DNA: This is not a standard or recognized modification involved in imprinting or gene expression regulation. Glycosylation generally refers to the addition of sugar moieties to proteins or lipids, not DNA.​

In summary, DNA methylation is the key mechanism responsible for maintaining genomic imprinting from one generation to another, while phosphorylation, acetylation, and glycosylation of DNA do not play significant roles in this context.

This article helps clarify that methylation of DNA is the central epigenetic modification ensuring the maintenance of imprinting patterns, with other options being unrelated or less relevant for this process.

Genomic imprinting maintenance DNA methylation is the key phrase that can help students and researchers find reliable information on this topic.