The most notable classes of biological macromolecules used in the fundamental processes of living organisms include: ( March 2015) ( Learn how and when to remove this template message) Unsourced material may be challenged and removed. Please help improve this section by adding citations to reliable sources. He also considered that, in general, there was only a remote possibility that non-carbon life forms would be able to evolve with genetic information systems capable of self-replication and adaptation. However, the results of this mission indicated that Mars was presently extremely hostile to carbon-based life. He considered that the great versatility of the carbon atom makes it the element most likely to provide solutions, even exotic solutions, to the problems of survival on other planets. mission, Viking Lander of 1976, to successfully land an unmanned probe on the surface of Mars. Norman Horowitz, was the head of the Jet Propulsion Laboratory’s bioscience section for the first U.S. "What we normally think of as 'life' is based on chains of carbon atoms, with a few other atoms, such as nitrogen or phosphorus", per Stephen Hawking in a 2008 lecture, "carbon has the richest chemistry." Carbon atoms bond readily to other carbon atoms this allows the building of arbitrarily long macromolecules and polymers in a process known as catenation. The most important characteristics of carbon as a basis for the chemistry of life are that each carbon atom is capable of forming up to four valence bonds with other atoms simultaneously, and that the energy required to make or break a bond with a carbon atom is at an appropriate level for building large and complex molecules which may be both stable and reactive. It is the second most abundant element in the human body by mass (about 18.5%) after oxygen. In a 2018 study, carbon was found to compose approximately 550 billion tons of all life on Earth. Carbon's widespread abundance, its ability to form stable bonds with numerous other elements, and its unusual ability to form polymers at the temperatures commonly encountered on Earth enables it to serve as a common element of all known living organisms. The branch of chemistry that studies organic compounds is known as organic chemistry.Ĭarbon is the 15th most abundant element in the Earth's crust, and the fourth most abundant element in the universe by mass, after hydrogen, helium, and oxygen. The enormous diversity of carbon-containing compounds, known as organic compounds, has led to a distinction between them and compounds that do not contain carbon, known as inorganic compounds. They believed that photonics were living, and that carbon-based lifeforms were artificial.Carbon is capable of forming a vast number of compounds, more than any other element, with almost ten million compounds described to date, and yet that number is but a fraction of the number of theoretically possible compounds under standard conditions. ( VOY: " Cold Fire")Ī species of naturally-occurring photonic lifeforms encountered by Voyager in 2375 were unaware of the existence of biochemical lifeforms. While scanning Suspiria's array for sporocystian lifeforms, the USS Voyager discovered instead the signatures of over two thousand carbon-based lifeforms. In spite of not being carbon-based, the silicate-based lifeform discovered on L-S VI in 2370 was determined to be vegetative, very much alive, and possibly akin to Odo. The internal environment of Gomtuu was suitable for carbon-based lifeforms. V'ger considered carbon units to be inferior, and not true lifeforms. V'ger and its Ilia probe used the term carbon unit to describe the humanoid crew of the USS Enterprise. The Starfleet Academy course " Exobiology 101" taught several basics on carbon-based life, such as that the Human immune system was unable to combat non-carbon elements, such as silicon and silicon-based viruses, which could attack the Human body in unpredictable ways. It was believed to be scientifically impossible for carbon cycle lifeforms to inhabit a planet like Excalbia, which had a poisonous atmosphere and surface consisting mostly molten lava, nonetheless, the planet was inhabited by a technologically advanced species. ( ENT: " Observer Effect" TNG: " Angel One") A carbon-based lifeform was any lifeform, including flora and fauna, that depends upon carbon atoms, and was almost exclusively found on M class planets.
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