Dr Paul Reynolds
Appreciate the higher order structure of DNA
X chromosome inactivation occurs during early embryonic development, it occurs in females not males, as females have XX, it happens at random and can change between every cell in your body.
it occurs due to an RNA molecule known as Xist. which is only expressed on the X-chromosome that is being inactivated.
gene imprinting is the silencing of genes an imprinted gene is one that has been silenced
DNA methylation is known as the silencing of genes, it occurs in promoter regions of CG (base pairs) known as CPG islands. it causes methylation of the Cystein groups causing a product of 5-methylcytosine to be produced. this process causes chromatin to go from an open to closed state and it causes regions of heterochromatin to be formed (non-transcriptionally active genes)
uniparental disomy occurs when there is a deficiency from either paternal or maternal genetic information. there are two types of uniparental disomy there is isodisomy and heterodisomy
Heterodisomy is caused by non-segregation in stage I meiosis, and the affected individual inherits two homologous chromosomes from the same parent