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J. B. S. Haldane
John Burdon Sanderson Haldane (; 5 November 18921 December 1964), nicknamed "Jack" or "JBS", was a British-born scientist who later moved to India and acquired Indian citizenship. He worked in the fields of physiology, genetics, evolutionary biology, and mathematics. With innovative use of statistics in biology, he was one of the founders of neo-Darwinism. Despite his lack of an academic degree in the field, he taught biology at the University of Cambridge, the Royal Institution, and University College London. Renouncing his British citizenship, he became an Indian citizen in 1961 and worked at the Indian Statistical Institute until his death in 1964. Haldane's article on abiogenesis in 1929 introduced the "primordial soup theory", which became the foundation for the concept of the chemical origin of life. He established human gene maps for haemophilia and colour blindness on the X chromosome, and codified Haldane's rule on sterility in the heterogametic sex of hybrids in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxford
Oxford () is a City status in the United Kingdom, cathedral city and non-metropolitan district in Oxfordshire, England, of which it is the county town. The city is home to the University of Oxford, the List of oldest universities in continuous operation, oldest university in the English-speaking world; it has buildings in every style of Architecture of England, English architecture since late History of Anglo-Saxon England, Anglo-Saxon. Oxford's industries include motor manufacturing, education, publishing, science, and information technologies. Founded in the 8th century, it was granted city status in 1542. The city is located at the confluence of the rivers Thames (locally known as the Isis) and River Cherwell, Cherwell. It had a population of in . It is north-west of London, south-east of Birmingham and north-east of Bristol. History The history of Oxford in England dates back to its original settlement in the History of Anglo-Saxon England, Saxon period. The name � ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Distribution
In probability theory and statistics, the beta distribution is a family of continuous probability distributions defined on the interval [0, 1] or (0, 1) in terms of two positive Statistical parameter, parameters, denoted by ''alpha'' (''α'') and ''beta'' (''β''), that appear as exponents of the variable and its complement to 1, respectively, and control the shape parameter, shape of the distribution. The beta distribution has been applied to model the behavior of random variables limited to intervals of finite length in a wide variety of disciplines. The beta distribution is a suitable model for the random behavior of percentages and proportions. In Bayesian inference, the beta distribution is the conjugate prior distribution, conjugate prior probability distribution for the Bernoulli distribution, Bernoulli, binomial distribution, binomial, negative binomial distribution, negative binomial, and geometric distribution, geometric distributions. The formulation of the beta dist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterotrophic Theory
Primordial soup, also known as prebiotic soup and Haldane soup, is the hypothetical set of conditions present on the Earth around 3.7 to 4.0 billion years ago. It is an aspect of the heterotrophic theory (also known as the Oparin–Haldane hypothesis) concerning the origin of life, first proposed by Alexander Oparin in 1924, and J. B. S. Haldane in 1929. As formulated by Oparin, in the primitive Earth's surface layers, carbon, hydrogen, water vapour, and ammonia reacted to form the first organic compounds. The concept of a primordial soup gained credence in 1953 when the "Miller–Urey experiment" used a highly reduced mixture of gases—methane, ammonia and hydrogen—to form basic organic monomers, such as amino acids. Historical background The notion that living beings originated from inanimate materials comes from the Ancient Greeks—the theory known as spontaneous generation. Aristotle in the 4th century BCE gave a proper explanation, writing: Aristotle also states that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neo-Darwinism
Neo-Darwinism is generally used to describe any integration of Charles Darwin's theory of evolution by natural selection with Gregor Mendel's theory of genetics. It mostly refers to evolutionary theory from either 1895 (for the combinations of Darwin's and August Weismann's theories of evolution) or 1942 (" modern synthesis"), but it can mean any new Darwinian- and Mendelian-based theory, such as the current evolutionary theory. Original use Darwin's theory of evolution by natural selection, as published in 1859, provided a selection mechanism for evolution, but not a trait transfer mechanism. Lamarckism was still a very popular candidate for this. August Weismann and Alfred Russel Wallace rejected the Lamarckian idea of inheritance of acquired characteristics that Darwin had accepted and later expanded upon in his writings on heredity. The basis for the complete rejection of Lamarckism was Weismann's germ plasm theory. Weismann realised that the cells that produce the germ pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Population Genetics
Population genetics is a subfield of genetics that deals with genetic differences within and among populations, and is a part of evolutionary biology. Studies in this branch of biology examine such phenomena as Adaptation (biology), adaptation, speciation, and population stratification, population structure. Population genetics was a vital ingredient in the emergence of the Modern synthesis (20th century), modern evolutionary synthesis. Its primary founders were Sewall Wright, J. B. S. Haldane and Ronald Fisher, who also laid the foundations for the related discipline of quantitative genetics. Traditionally a highly mathematical discipline, modern population genetics encompasses theoretical, laboratory, and field work. Population genetic models are used both for statistical inference from DNA sequence data and for proof/disproof of concept. What sets population genetics apart from newer, more phenotypic approaches to modelling evolution, such as evolutionary game theory and evolu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Resistance To Malaria
Human genetic resistance to malaria refers to inherited changes in the DNA of humans which increase resistance to malaria and result in increased survival of individuals with those genetic changes. The existence of these genotypes is likely due to evolutionary pressure exerted by parasites of the genus ''Plasmodium'' which cause malaria. Since malaria infects red blood cells, these genetic changes are most common alterations to molecules essential for red blood cell function (and therefore parasite survival), such as hemoglobin or other cellular proteins or enzymes of red blood cells. These alterations generally protect red blood cells from invasion by ''Plasmodium'' parasites or replication of parasites within the red blood cell. These inherited changes to hemoglobin or other characteristic proteins, which are critical and rather invariant features of mammalian biochemistry, usually cause some kind of inherited disease. Therefore, they are commonly referred to by the names of the b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Economy
The hydrogen economy is an umbrella term for the roles hydrogen can play alongside low-carbon electricity to reduce emissions of greenhouse gases. The aim is to reduce emissions where cheaper and more energy-efficient clean solutions are not available. In this context, ''hydrogen economy'' encompasses the production of hydrogen and the use of hydrogen in ways that contribute to phasing-out fossil fuels and limiting climate change. Hydrogen can be produced by several means. Most hydrogen produced today is ''gray hydrogen'', made from natural gas through steam methane reforming (SMR). This process accounted for 1.8% of global greenhouse gas emissions in 2021.Greenhouse gas emissions totalled 49.3 Gigatonnes CO2e in 2021. ''Low-carbon hydrogen'', which is made using SMR with carbon capture and storage ('' blue hydrogen''), or through electrolysis of water using renewable power ('' green hydrogen''), accounted for less than 1% of production. Virtually all of the 100 million tonnes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzymology
An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecules known as product (chemistry), products. Almost all metabolism, metabolic processes in the cell (biology), cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme, pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts include Ribozyme, catalytic RNA molecules, also called ribozymes. They are sometimes descr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Darwin (unit)
The darwin (d) is a unit of evolutionary change, defined by J. B. S. Haldane in 1949. J.B.S. Haldane (1949).Suggestions as to quantitative measurement of rates of evolution" ''Evolution'' 3:51–56. One darwin is defined to be an e-fold (about 2.718) change in a trait over one million years. Haldane named the unit after Charles Darwin. Equation The equation for calculating evolutionary change in darwins (r) is: :r=\frac where X_1 and X_2 are the initial and final values of the trait and \Delta t is the change in time in millions of years. An alternative form of this equation is: :r=\frac Since the difference between two natural logarithms is a dimensionless ratio, the trait may be measured in any unit. Inexplicably, Haldane defined the millidarwin as 10−9 darwins, despite the fact that the prefix milli- usually denotes a factor of one thousandth (10−3). Application The measure is most useful in palaeontology, where macroevolutionary changes in the dimensions of fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abiogenesis
Abiogenesis is the natural process by which life arises 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 a process of increasing complexity involving the formation of a habitable planet, the prebiotic synthesis of organic molecules, molecular self-replication, self-assembly, autocatalysis, and the emergence of cell membranes. The transition from non-life to life has never been observed experimentally, but 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 water, and builds largely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haldane's Dilemma
Haldane's dilemma, also known as the waiting time problem, is a limit on the speed of beneficial evolution, calculated by J. B. S. Haldane in 1957. Before the invention of DNA sequencing technologies, it was not known how much gene polymorphism, polymorphism DNA harbored, although alloenzymes (variant forms of an enzyme which differ structurally but not functionally from other alloenzymes coded for by different alleles at the same locus) were beginning to make it clear that substantial polymorphism existed. This was puzzling because the amount of polymorphism known to exist seemed to exceed the theoretical limits that Haldane calculated, that is, the limits imposed if polymorphisms present in the population generally influence an organism's fitness. Motoo Kimura's landmark paper on neutral theory in 1968 built on Haldane's work to suggest that most molecular evolution is neutral, resolving the dilemma. Although neutral evolution remains the consensus theory among modern biologist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
