The History of Terrorism
Preview
Open in TheBrain
Links
Container categories
Main topic classifications
Academic disciplines
Natural sciences
Physical sciences
Chemistry
Chemical reactions
Organic reactions
Methylation
Attachments
wikipedia
Parents
Chemical reactions
Epigenetics
Organic reactions
Post-translational modification
Children
1944?-1958 Methylated bases were discovered in DNA about 20 years ago and in RNA. in 1958. Until recently, however, no one had any idea how methyl groups got to be stuck onto the normally unmethylated bases in nucleic acids or what they were doing there.
1962 In 1962, with Erwin Fleissner, Borek showed that methyl groups in RNA that are essential in various biological roles in coding, decoding, regulation, and expression of genes are introduced to RNA by methylating enzymes at the macro-molecular level.
But, suppose something got Into a cell and upset the methylation pattern of the nucleic acids there.
DNA methylation
Dr. Borek's team has now shown, moreover, that none of the methylatable bases in one "breed" of RNA bears a methyl group, whereas a certain proportion of those bases...
Fourth, ultraviolet radiation, which, in excessive doses, causes cancer, has recently been found by Dr. Ryan to alter the normal levels of nucleic acid methylation in cells.
Methylating agents
Methylating enzymes
O-methylation
RNA methylation
Second, the largest amounts of methylated nucleic acid components ever reported have been found in tumor tissue. Whether unusually high levels of methylation, exist in other diseased tissues is not known but has not been seen yet.
The presumption here is that the breaks are caused by stresses in cellular DNA within the chromosomes resulting from the abnormal methylation of it by enzymes which tumor viruses introduce into, cells.
Third, abnorntally methylated nucleic acid components have been found both in animal tissues which have been exposed to chemical carcinogens and in excretions from human patients with different forms of cancer.
This means that each species has its own set of enzymes that methylate the bases in its nucleic acids in a distinctive way, as though there were some purpose to the process of methylation. But what purpose could methyl groups serve?
Thus, Dr. Borek feels, methy-' lated bases might give the DNA and RNA 'of each species their own distinctive shapes and in this way could help maintain the Individuality of a species.