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Proteinoids
Proteinoids, or thermal proteins, are protein-like, often cross-linked molecules formed abiotically from amino acids. Sidney W. Fox initially proposed that they may have been precursors to the first living cells ( protocells). The term was also used in the 1960s to describe peptides that are shorter than twenty amino acids found in hydrolysed protein, but this term is no longer commonly used. History In trying to uncover the intermediate stages of abiogenesis, scientist Sidney W. Fox in the 1950s and 1960s, studied the spontaneous formation of peptide structures under conditions that might plausibly have existed early in Earth's history. He demonstrated that amino acids could spontaneously form small chains called peptides. In one of his experiments, he allowed amino acids to dry out as if puddled in a warm, dry spot in prebiotic conditions. He found that, as they dried, the amino acids formed long, often cross-linked, thread-like microscopic polypeptide globules, he named "protein ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid residue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water
Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent). It is vital for all known forms of life, despite not providing food, energy or organic micronutrients. Its chemical formula, H2O, indicates that each of its molecules contains one oxygen and two hydrogen atoms, connected by covalent bonds. The hydrogen atoms are attached to the oxygen atom at an angle of 104.45°. "Water" is also the name of the liquid state of H2O at standard temperature and pressure. A number of natural states of water exist. It forms precipitation in the form of rain and aerosols in the form of fog. Clouds consist of suspended droplets of water and ice, its solid state. When finely divided, crystalline ice may precipitate in the form of snow. The gaseous state of water is steam or water vapor. Water co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protocell
A protocell (or protobiont) is a self-organized, endogenously ordered, spherical collection of lipids proposed as a stepping-stone toward the origin of life. A central question in evolution is how simple protocells first arose and how they could differ in reproductive output, thus enabling the accumulation of novel biological emergences over time, i.e. biological evolution. Although a functional protocell has not yet been achieved in a laboratory setting, the goal to understand the process appears well within reach. Overview Compartmentalization was important in the origins of life. Membranes form enclosed compartments that are separate from the external environment, thus providing the cell with functionally specialized aqueous spaces. As the lipid bilayer of membranes is impermeable to most hydrophilic molecules (dissolved by water), cells have membrane transport-systems that achieve the import of nutritive molecules as well as the export of waste. It is very challenging to cons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jeewanu
Jeewanu (Sanskrit for "particles of life") are synthetic chemical particles that possess Cell membrane, cell-like structure and seem to have some functional properties; that is, they are a model of primitive cells, or protocells. It was first synthesised by Krishna Bahadur (20 January 1926 — 5 August 1994), an Indian chemist and his team in 1963. Using photochemical reaction, they produced coacervates, microscopic cell-like spheres from a mixture of simple Organic compound, organic and inorganic compounds. Bahadur named these particles 'Jeewanu' because they exhibit some of the basic properties of a cell, such as the presence of semipermeable membrane, amino acids, phospholipids and carbohydrates. Further, like living cells, they had several catalytic activities. Jeewanu are cited as models of protocells for the Abiogenesis, origin of life,Gánti, T. (2003''The Principles of Life'' Oxford University Press. and as artificial cells. Etymology Jeewanu is derived from Sanskrit ''je ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abiogenesis
In biology, abiogenesis (from a- 'not' + Greek bios 'life' + genesis 'origin') or the origin of life is the natural process by which life has arisen from non-living matter, such as simple organic compounds. The prevailing scientific hypothesis is that the transition from non-living to living entities on Earth was not a single event, but an evolutionary process of increasing complexity that involved the formation of a habitable planet, the prebiotic synthesis of organic molecules, molecular self-replication, self-assembly, autocatalysis, and the emergence of cell membranes. Many proposals have been made for different stages of the process. The study of abiogenesis aims to determine how pre-life chemical reactions gave rise to life under conditions strikingly different from those on Earth today. It primarily uses tools from biology and chemistry, with more recent approaches attempting a synthesis of many sciences. Life functions through the specialized chemistry of carbon and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PAH World Hypothesis
The PAH world hypothesis is a speculative hypothesis that proposes that polycyclic aromatic hydrocarbons (PAHs), known to be abundant in the universe, including in comets, and assumed to be abundant in the primordial soup of the early Earth, played a major role in the origin of life by mediating the synthesis of RNA molecules, leading into the RNA world. However, as yet, the hypothesis is untested. Background The 1952 Miller–Urey experiment demonstrated the synthesis of organic compounds, such as amino acids, formaldehyde and sugars, from the original inorganic precursors the researchers presumed to have been present in the primordial soup (but is no longer considered likely). This experiment inspired many others. In 1961, Joan Oró found that the nucleotide base adenine could be made from hydrogen cyanide (HCN) and ammonia in a water solution. Experiments conducted later showed that the other RNA and DNA nucleobases could be obtained through simulated prebiotic chemistry with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RNA World
The RNA world is a hypothetical stage in the evolutionary history of life on Earth, in which self-replicating RNA molecules proliferated before the evolution of DNA and proteins. The term also refers to the hypothesis that posits the existence of this stage. Alexander Rich first proposed the concept of the RNA world in 1962, and Walter Gilbert coined the term in 1986. Alternative chemical paths to life have been proposed, and RNA-based life may not have been the first life to exist. Even so, the evidence for an RNA world is strong enough that the hypothesis has gained wide acceptance. The concurrent formation of all four RNA building blocks further strengthened the hypothesis. Regardless of its plausibility in a prebiotic scenario, the RNA world can serve as a model system for studying the origin of life. Like DNA, RNA can store and replicate genetic information; like protein enzymes, RNA enzymes (ribozymes) can catalyze (start or accelerate) chemical reactions that are crit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cross-link
In chemistry and biology a cross-link is a bond or a short sequence of bonds that links one polymer chain to another. These links may take the form of covalent bonds or ionic bonds and the polymers can be either synthetic polymers or natural polymers (such as proteins). In polymer chemistry "cross-linking" usually refers to the use of cross-links to promote a change in the polymers' physical properties. When "crosslinking" is used in the biological field, it refers to the use of a probe to link proteins together to check for protein–protein interactions, as well as other creative cross-linking methodologies. Although the term is used to refer to the "linking of polymer chains" for both sciences, the extent of crosslinking and specificities of the crosslinking agents vary greatly. As with all science, there are overlaps, and the following delineations are a starting point to understanding the subtleties. Polymer chemistry Crosslinking is the general term for the process of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proteins
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid residues ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colin Pittendrigh
Colin Stephenson Pittendrigh (October 13, 1918 – March 19, 1996) "Colin Pittendrigh, 'Father of biological clock,' dies at 77", March 25, 1996, accessed April 9, 2011. was a British-born who spent most of his adult life in the United States. Pittendrigh is regarded as the "father of the biological clock," and founded the modern field of alongside and Erwin Bünnin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cinder Cone
A cinder cone (or scoria cone) is a steep conical hill of loose pyroclastic fragments, such as volcanic clinkers, volcanic ash, or scoria that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruptions or lava fountains from a single, typically cylindrical, vent. As the gas-charged lava is blown violently into the air, it breaks into small fragments that solidify and fall as either cinders, clinkers, or scoria around the vent to form a cone that often is symmetrical; with slopes between 30 and 40°; and a nearly circular ground plan. Most cinder cones have a bowl-shaped crater at the summit. Mechanics of eruption Cinder cones range in size from tens to hundreds of meters tall and often have a bowl-shaped crater at the summit. They are composed of loose pyroclastic material (cinder or scoria), which distinguishes them from ''spatter cones'', which are composed of agglomerated volcanic bombs. The pyroclastic material making up a cinder ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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