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Pleiotropic
Pleiotropy (from Greek , 'more', and , 'way') occurs when one gene influences two or more seemingly unrelated phenotypic traits. Such a gene that exhibits multiple phenotypic expression is called a pleiotropic gene. Mutation in a pleiotropic gene may have an effect on several traits simultaneously, due to the gene coding for a product used by a myriad of cells or different targets that have the same signaling function. Pleiotropy can arise from several distinct but potentially overlapping mechanisms, such as gene pleiotropy, developmental pleiotropy, and selectional pleiotropy. Gene pleiotropy occurs when a gene product interacts with multiple other proteins or catalyzes multiple reactions. Developmental pleiotropy occurs when mutations have multiple effects on the resulting phenotype. Selectional pleiotropy occurs when the resulting phenotype has many effects on fitness (depending on factors such as age and gender). An example of pleiotropy is phenylketonuria, an inherited d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexual Selection
Sexual selection is a mode of natural selection in which members of one biological sex mate choice, choose mates of the other sex to mating, mate with (intersexual selection), and compete with members of the same sex for access to members of the opposite sex (intrasexual selection). These two forms of selection mean that some individuals have greater reproductive success than others within a population, for example because they are more Animal sexual behaviour, attractive or prefer more attractive partners to produce offspring. Successful males benefit from frequent mating and monopolizing access to one or more fertile females. Females can maximise the return on the energy they invest in reproduction by selecting and mating with the best males. The concept was first articulated by Charles Darwin who wrote of a "second agency" other than natural selection, in which competition between mate candidates could lead to speciation. The theory was given a mathematical basis by Ronald F ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edward Tatum
Edward Lawrie Tatum (December 14, 1909 – November 5, 1975) was an American geneticist. He shared half of the Nobel Prize in Physiology or Medicine in 1958 with George Beadle for showing that genes control individual steps in metabolism. The other half of that year's award went to Joshua Lederberg. Beadle and Tatum's key experiments involved exposing the bread mold ''Neurospora crassa'' to x-rays, causing mutations. In a series of experiments, they showed that these mutations caused changes in specific enzymes involved in metabolic pathways. These experiments, published in 1941, led them to propose a direct link between genes and enzymatic reactions, known as the "one gene, one enzyme" hypothesis. Tatum went on to study genetics in bacteria. An active area of research in his laboratory was to understand the basis of Tryptophan biosynthesis in ''Escherichia coli''. Later, Tatum and his student Joshua Lederberg showed that ''E. coli'' could share genetic information through re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
George Beadle
George Wells Beadle (October 22, 1903 – June 9, 1989) was an American geneticist. In 1958 he shared one-half of the Nobel Prize in Physiology or Medicine with Edward Tatum for their discovery of the role of genes in regulating biochemical events within cells. He also served as the 7th President of the University of Chicago. Beadle and Tatum's key experiments involved exposing the bread mold ''Neurospora crassa'' to x-rays, causing mutations. In a series of experiments, they showed that these mutations caused changes in specific enzymes involved in metabolic pathways. These experiments led them to propose a direct link between genes and enzymatic reactions, known as the One gene-one enzyme hypothesis. Education and early life George Wells Beadle was born in Wahoo, Nebraska. He was the son of Chauncey Elmer Beadle and Hattie Albro, who owned and operated a farm nearby. George was educated at the Wahoo High School and might himself have become a farmer if one of his teachers a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Research
Research is "creativity, creative and systematic work undertaken to increase the stock of knowledge". It involves the collection, organization and analysis of evidence to increase understanding of a topic, characterized by a particular attentiveness to controlling sources of bias and error. These activities are characterized by accounting and controlling for biases. A research project may be an expansion on past work in the field. To test the validity of instruments, procedures, or experiments, research may replicate elements of prior projects or the project as a whole. The primary purposes of basic research (as opposed to applied research) are documentation, Discovery (observation), discovery, interpretation (philosophy), interpretation, and the research and development (R&D) of methods and systems for the advancement of human knowledge. Approaches to research depend on epistemology, epistemologies, which vary considerably both within and between humanities and sciences. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theory
A theory is a rational type of abstract thinking about a phenomenon, or the results of such thinking. The process of contemplative and rational thinking is often associated with such processes as observational study or research. Theories may be scientific, belong to a non-scientific discipline, or no discipline at all. Depending on the context, a theory's assertions might, for example, include generalized explanations of how nature works. The word has its roots in ancient Greek, but in modern use it has taken on several related meanings. In modern science, the term "theory" refers to scientific theories, a well-confirmed type of explanation of nature, made in a way consistent with the scientific method, and fulfilling the criteria required by modern science. Such theories are described in such a way that scientific tests should be able to provide empirical support for it, or empirical contradiction ("falsify") of it. Scientific theories are the most reliable, rigorous, and compr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Locus (genetics)
In genetics, a locus (plural loci) is a specific, fixed position on a chromosome where a particular gene or genetic marker is located. Each chromosome carries many genes, with each gene occupying a different position or locus; in humans, the total number of protein-coding genes in a complete haploid set of 23 chromosomes is estimated at 19,000–20,000. Genes may possess multiple variants known as alleles, and an allele may also be said to reside at a particular locus. Diploid and polyploid cells whose chromosomes have the same allele at a given locus are called homozygous with respect to that locus, while those that have different alleles at a given locus are called heterozygous. The ordered list of loci known for a particular genome is called a gene map. Gene mapping is the process of determining the specific locus or loci responsible for producing a particular phenotype or biological trait. Association mapping, also known as "linkage disequilibrium mapping", is a method of ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mechanism (biology)
In the science of biology, a mechanism is a system of causally interacting parts and processes that produce one or more effects. Scientists explain phenomena by describing mechanisms that could produce the phenomena. For example, natural selection is a mechanism of biological evolution; other mechanisms of evolution include genetic drift, mutation, and gene flow. In ecology, mechanisms such as predation and host-parasite interactions produce change in ecological systems. In practice, no description of a mechanism is ever complete because not all details of the parts and processes of a mechanism are fully known. For example, natural selection is a mechanism of evolution that includes countless, inter-individual interactions with other individuals, components, and processes of the environment in which natural selection operates. Characterizations/ definitions Many characterizations/definitions of mechanisms in the philosophy of science/biology have been provided in the past decade ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hans Grüneberg
Hans Grüneberg (26 May 1907 – 23 October 1982), whose name was also written as Hans Grueneberg and Hans Gruneberg, was a British geneticist. Grüneberg was born in Wuppertal–Elberfeld in Germany. He obtained an MD from the University of Bonn, a PhD in biology from the University of Berlin and a DSc from the University of London. He arrived in London in 1933, at the invitation of J.B.S. Haldane and Sir Henry Dale. He was elected a Fellow of the Royal Society in 1956. Most of his work focused on mouse genetics, in which his speciality was the study of pleiotropic effects of mutations on the development of the mouse skeleton. He was the first person to describe siderocytes and sideroblasts, atypical nucleated erythrocytes with granules of iron accumulated in perinuclear mitochondria. This he reported in the journal ''Nature''. The Grüneberg ganglion, an olfactory ganglion in rodents, was first described by Hans Grueneberg in 1973. Career * Honorary Research Assistant, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Festschrift
In academia, a ''Festschrift'' (; plural, ''Festschriften'' ) is a book honoring a respected person, especially an academic, and presented during their lifetime. It generally takes the form of an edited volume, containing contributions from the honoree's colleagues, former pupils, and friends. ''Festschriften'' are often titled something like ''Essays in Honour of...'' or ''Essays Presented to... .'' Terminology The term, borrowed from German, and literally meaning 'celebration writing' (cognate with ''feast-script''), might be translated as "celebration publication" or "celebratory (piece of) writing". An alternative Latin term is (literally: 'book of friends'). A comparable book presented posthumously is sometimes called a (, 'memorial publication'), but this term is much rarer in English. A ''Festschrift'' compiled and published by electronic means on the internet is called a (pronounced either or ), a term coined by the editors of the late Boris Marshak's , ''Eran ud Aner ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ludwig Plate
Ludwig Hermann Plate (16 August 1862 – 16 November 1937) was a German zoologist and student of Ernst Haeckel. He wrote a "thorough and extensive defence" of Darwinism, but before Mendel's work had been assimilated in the modern synthesis. Born in Bremen, Plate studied mathematics and natural sciences Bonn and in Jena, where he attended the lectures of Ernst Haeckel. In 1888, he achieved the 'Habilitation' in zoology at the University of Marburg. He was offered the Chair of Zoology at Jena University in 1909 through the help of Haeckel, and also became director of the Jena "Phyletisches Museum". Levit, Georgy S; Olsson, Lennart. (2007). ''Evolution on Rails Mechanisms and Levels of Orthogenesis''. In Volker Wissemann. ''Annals of the History and Philosophy of Biology 11/2006''. Universitätsverlag Göttingen. pp. 113-115. He coined the term Pleiotropy. Evolutionary views Plate was a proponent of what he called ''old-Darwinism'' or ''orthoevolution'', which included a supp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Correlation And Dependence
In statistics, correlation or dependence is any statistical relationship, whether causal or not, between two random variables or bivariate data. Although in the broadest sense, "correlation" may indicate any type of association, in statistics it usually refers to the degree to which a pair of variables are ''linearly'' related. Familiar examples of dependent phenomena include the correlation between the height of parents and their offspring, and the correlation between the price of a good and the quantity the consumers are willing to purchase, as it is depicted in the so-called demand curve. Correlations are useful because they can indicate a predictive relationship that can be exploited in practice. For example, an electrical utility may produce less power on a mild day based on the correlation between electricity demand and weather. In this example, there is a causal relationship, because extreme weather causes people to use more electricity for heating or cooling. However ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
