Both mechanisms regulate gene expression at the molecular level. DNA methylation is a mechanism that silences or represses gene expression. This occurs when a methyl group bonds to the DNA molecule. The methyl group works like a switch and “turns off” the expression of that particular gene. Histone remodeling is the reaction that occurs when histones change shape. DNA is coiled around the histones, so when the histone’s shape changes, the DNA’s shape changes too. Histone acetylation occurs when an acetyl group is added to the tail of the histone, as a result the DNA is coiled more loosely around the histone, consequently increasing gene expression. Histone deacetylation causes the opposite to occur. When the histone tails are deacetylated, the DNA becomes coiled more tightly around the histone, decreasing gene expression (Rettner, …show more content…
In a study conducted by Kaminsky, Zachary, et al. the purpose was to determine if microarray-based epigenetic profiling done on a set of monozygotic twins could reliably detect any differences in DNA methylation. They also used several different psychometric tests to determine any major psychological differences between the set of twins and gathered a detail history from each twin to determine if links could be made from the differing aspects of their lives to the detected epigenetic differences. Each twin was given The Wechsler Abbreviated Scale of Intelligence (WASI; Wechsler, 1999), The Minnesota Multiphasic Personality Inventory (MMPI-II; Hathaway, 1989), and The Toronto Gambling task (Floden & Stuss, 2004) to determine any differences in IQ, personality, psychopathology, and the amount or impulsiveness and risk-taking propensity, respectively. Each twin was also given zygosity testing to confirm that they were in fact monozygotic twins. They were each given epigenetic testing as well, focusing on DNA methylation. On the IQ test both twins scores were nearly identical and the zygosity test confirmed that they were indeed monozygotic twins. The rest of the tests showed the twins to be remarkably different. The MMPI test showed both twins to have drastically different