Carbon forms the backbone of biology for all life on Earth. Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Foundations of modern biology There are five unifying principles Life is a state that distinguishes Organisms from non-living objects such as non-life and dead organisms being manifested by growth through Metabolism EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 Complex molecules are made up of carbon bonded with other elements, especially oxygen, hydrogen and nitrogen. In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by A chemical bond is the physical process responsible for the attractive interactions between Atoms and Molecules and which confers stability to diatomic and polyatomic A chemical element is a type of Atom that is distinguished by its Atomic number; that is by the number of Protons in its nucleus. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 It is these elements that living organisms need, among others, and carbon is able to bond with all of these because of its four valence electrons. In chemistry valence electrons are the Electrons contained in the outermost or valence, Electron shell of an Atom. Since no life has been observed that is not carbon-based, it is sometimes assumed in astrobiology that life elsewhere in the universe will also be carbon-based. Astrobiology (from Greek grc ἄστρον astron, "constellation star" grc βίος bios, "life" and grc -λογία The Universe is defined as everything that Physically Exists: the entirety of Space and Time, all forms of Matter, Energy This assumption is referred to by critics as carbon chauvinism, as it may be possible for life to form that is not based on carbon, even though it has never been observed. Carbon chauvinism is a relatively new term meant to disparage the assumption that Extraterrestrial life will resemble life on Earth

In cinematic and literary science fiction, a moment when man-made machines cross from nonliving to living is often posited, this new form being the first example of non-carbon-based life. Since the advent of the microprocessor in the late 1960s, these machines are often classed as computers (or computer-guided robots) and filed under "silicon-based life", even though the silicon backing matrix of these processors is not nearly as fundamental to their operation as carbon is for "wet life". A microprocessor incorporates most or all of the functions of a Central processing unit (CPU on a single Integrated A computer is a Machine that manipulates data according to a list of instructions. A robot is a mechanical or Virtual Artificial agent In practice it is usually an electro-mechanical system which by its appearance or movements Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14

Characteristics of carbon as a basis for life

The two most important characteristics of carbon as a basis for the chemistry of life are that it has four valence bonds and that the energy required to make or break a bond is just at an appropriate level for building molecules which are not only stable but also reactive. Chemistry (from Egyptian kēme (chem meaning "earth") is the Science concerned with the composition structure and properties

The fact that carbon atoms bond readily to other carbon atoms allows for the building of arbitrarily long and complex molecules. An organic compound is any member of a large class of Chemical compounds whose Molecules contain Carbon.

There are not many other elements which appear to be even promising candidates for supporting life-like behavior, but the most frequent alternative suggested is silicon. Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 This is in the same group in the Periodic Table of elements and therefore also has four valence bonds. The periodic table of the chemical elements is a tabular method of displaying the Chemical elements Although precursors to this table exist its invention is A chemical element is a type of Atom that is distinguished by its Atomic number; that is by the number of Protons in its nucleus. In Chemistry, valence bond theory explains the nature of a Chemical bond in a Molecule in terms of atomic valencies. It also bonds to itself, but generally in the form of crystal lattices rather than long chains. In Mineralogy and Crystallography, a crystal structure is a unique arrangement of Atoms in a Crystal. However, its compounds are generally highly stable and do not support the ability to readily re-combine in different permutations in a manner that would plausibly support life-like processes.

This speculation of a life based on the chemistry of silicon is clearly distinct from "silicon-based life" in the above sense of artificial intelligence based on electronic processes utilizing silicon integrated circuits. Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 Microchipsjpg|right|thumb|200px|Microchips ( EPROM memory with a transparent window showing the integrated circuit inside

Key carbon-based molecules in the life processes

The most notable groups of chemicals used in the processes of living organisms include:

• Proteins, which are the building blocks from which the structures of living organisms are constructed
• Nucleic acids, which carry genetic information
• Enzymes, which catalyse organic chemical reactions
• Carbohydrates, which store energy in a form that can be used by living cells
• Fats, which also store energy, but in a more concentrated form, and which may be stored for extended periods in the bodies of animals. Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl A nucleic acid is a Macromolecule composed of chains of monomeric Nucleotides In Biochemistry these Molecules carry Genetic information Enzymes are Biomolecules that catalyze ( ie increase the rates of Chemical reactions Almost all enzymes are Proteins Catalysis is the process in which the rate of a Chemical reaction is increased by means of a Chemical substance known as a catalyst Carbohydrates (from ' Hydrates of Carbon ' or saccharides ( Greek σάκχαρον meaning " Sugar " are the most The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called Lipids are broadly defined as any fat- Soluble ( lipophilic) naturally-occurring Molecule, such as fats oils waxes cholesterol sterols fat-soluble

See also

• Alternative biochemistry

References

• Encyclopedia of Astrobiology, Astronomy & Spaceflight. Alternative biochemistry is the speculative Biochemistry of alien Life forms that differ radically from those on Earth. Retrieved on 2006-03-14. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 1489 - The Queen of Cyprus, Catherine Cornaro, sells her kingdom to Venice.