Purines and pyrimidines are nitrogen bases found in DNA and RNA .They are nitrogen containing heterocyclic compounds .Purines are large double ringed while pyrimidines are sma â¦ ll single ringed .
Frozen Methane is exactly what it sounds like. Frozen methane. Or in other words, it's methane locked in ice, which is called hydrates. It is also known as fire ice, because of it's ice-like appearance and ability to burn when lit with a match. Frozen Methane is formed when a large amount of methane is trapped within a crystal structure of water, forming a solid similar to ice.
Methane is a potent greenhouse gas that is capable of trapping large amounts of heat in the atmosphere. As it was replaced with oxygen, the temperature of the Earth cooled drastically. This cooling, between 2400 million years ago and 2100 million years ago, gave rise to the Huronian glaciation (Melezhik, 2006).