Mutation Monday (Your Mutation Station): Cytosine deamination

Due to simple chemistry, the nucleotide base cytosine undergoes a common, but unintended reaction  with water, resulting in loss of its ammonia and conversion of the base from cytosine to uracil.  This is known as cytosine deamination and is a natural process, that results in a constant assault on our DNA, causing damage due to the aqueous environment surrounding the DNA molecule.  This leads to a point mutation, but is usually easily picked up by the proof-reading properties of DNA polymerase (the enzyme that copies the DNA molecule). It is easily picked up because uracil is not a natural base in DNA.  It is found normally in RNA, and it is quite possible that RNA evolved first in the earliest life on earth, and when DNA took over the role it has today of storing genetic information thymine was substituted in place of uracil so that the deamination process could be detected and repaired.  In other words, if uracil was

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Origins Sunday: Building blocks of nucleotides

The building blocks for nucleotide bases seem to be capable of forming in hot conditions, like those found around deep sea hydrothermal vents.  Nucleotides are made of rings of carbon with nitrogen atoms in the ring structure.  These rings were not thought to form easily in the cold conditions of the gas clouds in space, but may form readily in these hydrothermal vent conditions.  On early earth this might of provided the building blocks for DNA and RNA molecules. And…Happy Father’s Day! http://www.astrobio.net/topic/origins/origin-and-evolution-of-life/a-hot-start-to-the-origin-of-life/