Carbon-based life

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Carbon is a key component of all known life on Earth, which represents about 45-50% of all dry biomass. The complex molecule consists of carbon bonds with other elements, especially oxygen and hydrogen and often also with nitrogen, phosphorus and sulfur. Carbon is abundant on Earth. It's also lightweight and relatively small in size, making it easier for enzymes to manipulate carbon molecules. It is often assumed in astrobiology that if life existed elsewhere in the universe, it would also be carbon-based. Criticism refers to this assumption as carbon chauvinism .

Video Carbon-based life

Characteristics

"What we usually think of as 'life' is based on a chain of carbon atoms, with some other atoms, like nitrogen or phosphorus," per Stephen Hawking in a 2008 lecture, "carbon [...] has the richest chemistry." The most important characteristic of carbon as the basis for the chemistry of life is that it has four valence bonds, and that the energy required to make or break bonds is at the right level for building molecules, which are stable and reactive. The bonds of carbon atoms are ready for other carbon atoms; this allows the formation of complex molecules and polymers that are too long.

Maps Carbon-based life

Other Candidates

Not many other elements are even seemingly promising candidates for life support, for example, processes such as metabolism. The most commonly recommended alternative is silicon. Silicon is in the same group in the Periodic Table of elements, and has four valence bonds, and bonds for itself, generally in the form of a crystal lattice rather than a long chain. It's much more electropositive than carbon. The silicon compound does not readily recombine into different permutations in a way that will support the real process.

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Main molecule

The most important groups of chemicals used in living organism processes include:

• Proteins, which are the building blocks from which the structure of living organisms are built (this includes almost all enzymes, which catalyze organic chemical reactions)
• Nucleic acid, which carries genetic information
• Carbohydrates, which store energy in a form that can be used by living cells
• Lipids, which also store energy, but in a more concentrated form, and which can be stored for a long time in the animal body

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Fiction

Silicon has become a non-carbon based life theme because it is somewhat similar to carbon in its chemical characteristics. In cinematic and literary science fiction, when man-made machinery shifts from non-living to life, this new form will be an example of non-carbon-based life. Since the advent of microprocessors in the late 1960s, these machines have often been classified as "silicon-based life". Another example of "silicone-based life" is the episode of "The Devil in the Dark" from Star Trek: The Original Series, in which biochemical living things are based on silicon. Also in The X-Files episode "Firewalker" in which silicon-based organisms are found in volcanoes.

In the adaptation of Arthur C. Clarke's film "2010" (1984) a character argues, "Whether we are grounded in carbon or on silicon makes no fundamental difference, each of us must be treated with the proper respect". This quote might be the basis of Steve Jobs's quote when he introduced Carbon in MacOS X, "Carbon. All life forms will be based on it."

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See also

• hypothetical biochemical type
• CHONPS, the mnemonic acronym for the most common element in living organisms: c arbon, h ydrogen, o xygen, and n itrogen, p phosphorus, s ulfur

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References

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External links

• "Encyclopedia of Astrobiology, Astronomy & Spaceflight" . Retrieved 2006/03/14
• "Chemistry School, University of Bristol, United Kingdom".

Source of the article : Wikipedia