Carbon Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds. There are three naturally occurring isotopes, with 12C and 13C being stable, while 14C is radioactive, decaying with a half-life of forms the backbone of biology Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy for all life Life is a characteristic that distinguishes objects that have signaling and self-sustaining processes (biology) from those that do not, either because such functions have ceased (death), or else because they lack such functions and are classified as inanimate on Earth Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets. It is sometimes referred to as the World, the Blue Planet,[note 6] or by its Latin name, Terra.[note 7]. Complex molecules A molecule is defined as an electrically neutral group of at least two atoms in a definite arrangement held together by very strong chemical bonds. Molecules are distinguished from polyatomic ions in this strict sense. In organic chemistry and biochemistry, the term molecule is used less strictly and also is applied to charged organic molecules are made up of carbon bonded A chemical bond is an attraction between atoms or molecules and allows the formation of chemical compounds, which contain two or more atoms. A chemical bond is the attraction caused by the electromagnetic force between opposing charges, either between electrons and nuclei, or as the result of a dipole attraction. The strength of bonds varies with other elements A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. The term is also used to refer to a pure chemical substance composed of atoms with the same number of protons. Common examples of elements are iron, copper, silver, gold, hydrogen, carbon,, especially oxygen Oxygen (pronounced /ˈɒksɨdʒɨn/, OK-si-jin, from the Greek roots ὀξύς (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter), is the element with atomic number 8 and represented by the symbol O. It is a member of the chalcogen group on the periodic table, and is a highly, hydrogen Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of 1.00794 u (1.007825 u for Hydrogen-1), hydrogen is the lightest and most abundant chemical element, constituting roughly 75 % of the Universe's elemental mass. Stars in the main sequence are mainly composed of hydrogen in its and nitrogen Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere, and carbon is able to bond with all of these because of its four valence electrons In chemistry, valence electrons are the outermost electrons of an atom, which are important in determining how the atom reacts chemically with other atoms. Atoms with a complete shell of valence electrons tend to be chemically inert. Atoms with one or two valence electrons more than a closed shell are highly reactive because the extra electrons. It is often assumed in astrobiology Astrobiology is the study of the origin, evolution, distribution, and future of life in the universe. Earth is the only known inhabited planet in the universe to date. However, advancements in the fields of astrobiology, observational astronomy and discovery of large varieties of extremophiles with extraordinary capability to thrive in harshest that if life exists somewhere else in the universe The Universe is commonly defined as the totality of everything that exists, including all physical matter and energy, the planets, stars, galaxies, and the contents of intergalactic space, although this usage may differ with the context . The term Universe may be used in slightly different contextual senses, denoting such concepts as the cosmos,, it will also be carbon based. This assumption is referred to by critics as carbon chauvinism 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 Science fiction is a genre of fiction dealing with the impact of imagined innovations in science or technology. It differs from fantasy in that, within the context of the story, its imaginary elements are largely possible within scientifically established or scientifically postulated laws of nature . Exploring the consequences of such differences, a moment when man-made machines cross from nonliving to living, is often posited,[citation needed] this new form would be the first example of non-carbon-based life. Since the advent of the microprocessor A microprocessor incorporates most or all of the functions of a computer's central processing unit on a single integrated circuit (IC, or microchip). The first microprocessors emerged in the early 1970s and were used for electronic calculators, using binary-coded decimal (BCD) arithmetic in 4-bit words. Other embedded uses of 4-bit and 8-bit in the late 1960s, these machines are often classed as computers A computer is a programmable machine that receives input, stores and manipulates data//information, and provides output in a useful format (or computer-guided robots A robot is an automatically guided machine which is able to do tasks on its own, almost always due to electronically-programmed instructions. Another common characteristic is that by its appearance or movements, a robot often conveys a sense that it has intent or agency of its own) and filed under "silicon Silicon is the most common metalloid. It is a chemical element, which has the symbol Si and atomic number 14. A tetravalent metalloid, silicon is less reactive than its chemical analog carbon. It is the eighth most common element in the universe by mass, but silicon very rarely occurs as the pure free element in nature. Silicon is more widely-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".
Contents |
Characteristics of carbon as a basis for life
The two most important characteristics of carbon as a basis for the chemistry Chemistry is the science of matter and the changes it undergoes. The science of matter is also addressed by physics, but while physics takes a more general and fundamental approach, chemistry is more specialized, being concerned with the composition, behavior, structure, and properties of matter, as well as the changes it undergoes during chemical 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. 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. For historical reasons discussed below, a few types of compounds such as carbonates, simple oxides of carbon and cyanides, as well as the allotropes of carbon, are considered inorganic. The distinction between "organic" and ".
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 is the most common metalloid. It is a chemical element, which has the symbol Si and atomic number 14. A tetravalent metalloid, silicon is less reactive than its chemical analog carbon. It is the eighth most common element in the universe by mass, but silicon very rarely occurs as the pure free element in nature. Silicon is more widely.[citation needed] This is in the same group in the Periodic Table The periodic table of the chemical elements is a tabular display of the chemical elements. Although precursors to this table exist, its invention is generally credited to Russian chemist Dmitri Mendeleev in 1869, who intended the table to illustrate recurring ("periodic") trends in the properties of the elements. The layout of the table of elements A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. The term is also used to refer to a pure chemical substance composed of atoms with the same number of protons. Common examples of elements are iron, copper, silver, gold, hydrogen, carbon, and therefore also has four valence bonds In chemistry, valence bond theory is one of two basic theories, along with molecular orbital theory, that developed to use the methods of quantum mechanics to explain chemical bonding. It focuses on how the atomic orbitals of the dissociated atoms combine on molecular formation to give individual chemical bonds. In contrast, molecular orbital. It also bonds to itself, but generally in the form of crystal lattices In mineralogy and crystallography, crystal structure is a unique arrangement of atoms or molecules in a crystalline liquid or solid. A crystal structure is composed of a pattern, a set of atoms arranged in a particular way, and a lattice exhibiting long-range order and symmetry. Patterns are located upon the points of a lattice, which is an array, less amenable to a complete source of life, rather than long chains. 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 Artificial intelligence is the intelligence of machines and the branch of computer science that aims to create it. Textbooks define the field as "the study and design of intelligent agents," where an intelligent agent is a system that perceives its environment and takes actions that maximize its chances of success. John McCarthy, who based on electronic processes utilizing silicon integrated circuits In electronics, an integrated circuit is a miniaturized electronic circuit (consisting mainly of semiconductor devices, as well as passive components) that has been manufactured in the surface of a thin substrate of semiconductor material. Integrated circuits are used in almost all electronic equipment in use today and have revolutionized the.
Key carbon-based molecules in the life processes
The most notable groups of chemicals used in the processes of living organisms include:
- Proteins Proteins are organic compounds made of amino acids arranged in a linear chain and folded into a globular form. The amino acids in a polymer are joined together by the peptide bonds between the carboxyl and amino groups of adjacent amino acid residues. The sequence of amino acids in a protein is defined by the sequence of a gene, which is encoded, which are the building blocks from which the structures of living organisms are constructed (this includes almost all enzymes Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, called the products. Almost all processes in a biological cell need enzymes to occur at significant rates. Since enzymes are selective for their, which catalyse Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself. A catalyst may participate in multiple chemical transformations. Catalysts that speed the reaction are called positive organic chemical reactions
- Nucleic acids A nucleic acid is a macromolecule composed of chains of monomeric nucleotides. In biochemistry these molecules carry genetic information or form structures within cells. The most common nucleic acids are deoxyribonucleic acid and ribonucleic acid (RNA). Nucleic acids are universal in living things, as they are found in all cells and viruses, which carry genetic Genetics , a discipline of biology, is the science of heredity and variation in living organisms. The fact that living things inherit traits from their parents has been used since prehistoric times to improve crop plants and animals through selective breeding. However, the modern science of genetics, which seeks to understand the process of information
- Carbohydrates A carbohydrate is an organic compound with the general formula Cmn, that is, consists only of carbon, hydrogen and oxygen, with the last two in the 2:1 atom ratio. Carbohydrates can be viewed as hydrates of carbon, hence their name. Structurally however, it is more accurate to view them as polyhydroxy aldehydes and ketones, which store energy in a form that can be used by living cells The cell is the functional basic unit of life. It was discovered by Robert Hooke and is the functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. Some organisms, such as most bacteria, are unicellular . Other organisms, such as humans,
- Fats Lipids are a broad group of naturally occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, phospholipids, and others. The main biological functions of lipids include energy storage, as structural components of cell membranes, and as important signaling molecules, which also store energy, but in a more concentrated form, and which may be stored for extended periods in the bodies of animals.
See also
- Hypothetical types of biochemistry The hypothetical types of biochemistry are the different types of speculative biochemistries of alien life forms that differ radically from those known on Earth. It includes biochemistries that use elements other than carbon for its basic structural and physiological functions and/or use solvents other than water. Theories about extraterrestrial
- CHON The Chon languages were spoken in Tierra del Fuego and Patagonia. Two were known to exist - Selk'nam, which went extinct in 2003, and Tehuelche. The Selk'nam people were widely studied by anthropologists such as Martin Gusinde and Anne Chapman, throughout the 20th century; however, their language was not preserved Mnemonic acronym for the most common elements in living organisms: Carbon, Hydrogen, Oxygen, and Nitrogen.
References
External links
- "Encyclopedia of Astrobiology, Astronomy & Spaceflight". http://www.daviddarling.info/encyclopedia/C/carbon-based_life.html. Retrieved 2006-03-14.
- "School of Chemistry, University of Bristol, United Kingdom". http://www.chm.bris.ac.uk/webprojects1997/ClaireO/Welcome.htm. Retrieved 2000-01-01.
Categories: Astrobiology Categories: Astronomical sub-disciplines | Space exploration | Biology and pharmacology of chemical elements Categories: Biochemistry | Pharmacology | Properties of chemical elements
unknown
ue, 22 Jun 2010 07:05:00 GM
The element . carbon. forms the basis of all organic and biochemistry, the chemistry of . life. itself. . Life. on Earth is . Carbon based. and we humans, to use a phrase made famous by the late Arthur C. Clarke, are . Carbon Based. Bipeds . ...
