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Packing of DNA is required are DNA molecules in eukaryotes is very large. DNA therefore packs itself up into structures referred to as chromosomes. This allows DNA to be stored within the nucleus of cells. The process is simple, with DNA being the lowest for of storage, moving to nucleosomes, which is protein interacting with…

Genomic imprinting affects several dozen mammalian genes and results in the expression of those genes from only one of the two parental chromosomes (Reik and Walter, 2001). These mammalian genes function differently depending on whether they came from the mother or the father (Susani et al., 1984; McGrath and Solter, 1984). A key molecular mechanism…

In the loop domain model, inactive DNA is heterchromatin, with methylated DNA and hypoacetylated histones. Active DNA, is euchromatin, and has hyperacetylated histones and unmethylated DNA. Chromatin fibers are attached within the nucleus to nuclear matrix component structures through specific DNA binding proteins. This creates ‘loop domains’ within the nucleus, as it compartmentalizes sections of…

Histones are key regulators of gene expression, through numerous well-known chemical modifications. These include acetylation, phosphorylation, methylation, and ubiquitylation. For example, methylating and/or acetylating specific lysine residues of the nucleosomal cores of histones, such as lysine8, alter the chromatin structure, through interacting with the methylation machinery, and gene expression (1). DNA Methylation Machinery, Histone Deacetylases…

In comparison to CpG islands, which are found in the regulatory regions of genes, and are prime importance in the transcription of the regulators of cell growth and death, repetitive sequences, also known as endoparasitic sequences, which are transposable elements, inserting themselves into any sequence they please throughout the genome, are thankfully in normal cells,…

Cytosine methylation of DNA at CpG dinucleotides is the most well-known epigenetic change. Less than 10% of all cytosines are methylated in the human genome (1). These CpG dinucleotides are also not found randomly throughout the genome, but in finite areas, specifically clustered at the 5′ region of genes, in the promoter, untranslated region, and…

DNA Transcription – Nuclear compartmentalization, chromatin remodelling, recruitment of transcription machinery, transcription initiation, elongation, termination andpolyadenylation Splicing of mRNA Transport of mRNA out of Nucleus to Cytoplasm Localization and/or Degradation of mRNA Translation – localization, cleavage, degradation, covalent modification