Epigenetics

1340 WordsJan 31, 20136 Pages
ONE of biology’s hottest topics is epigenetics. The term itself covers a multitude of sins. Strictly speaking, it refers to the regulation of gene expression by the chemical modification of DNA, or of the histone proteins in which DNA is usually wrapped. This modification is either the addition of methyl groups (a carbon atom and three hydrogens) to the DNA or of acetyl groups (two carbons, three hydrogens and an oxygen) to the histones. Methylation switches genes off. Acetylation switches them on. Since, in a multicellular organism, different cells need different genes to be active, such regulation is vital. What has got a lot of people excited, though, is the idea that epigenetic switches might be transmitted down the generations.…show more content…
The term itself covers a multitude of sins. Strictly speaking, it refers to the regulation of gene expression by the chemical modification of DNA, or of the histone proteins in which DNA is usually wrapped. This modification is either the addition of methyl groups (a carbon atom and three hydrogens) to the DNA or of acetyl groups (two carbons, three hydrogens and an oxygen) to the histones. Methylation switches genes off. Acetylation switches them on. Since, in a multicellular organism, different cells need different genes to be active, such regulation is vital. What has got a lot of people excited, though, is the idea that epigenetic switches might be transmitted down the generations. Some see this as contrary to Darwinism, since it would permit characteristics acquired during an organism’s lifetime to be passed on to its offspring, as suggested by a rival theory of evolution put forward by Jean-Baptiste Lamarck. This is an exaggeration. The DNA sequence itself is not being permanently altered. Even those epigenetic changes that are inherited seem to be subsequently reversible. But the idea that acquired characteristics can be inherited at all is still an important and novel one, and a worrying example of the phenomenon has been published this week in BioMed Central Medicine. In this section * Lake monsters * A third-world dimension *
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