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Complete Linkage
In genetics, complete (or absolute) linkage is defined as the state in which two loci are so close together that alleles of these loci are virtually never separated by crossing over. The closer the physical location of two genes on the DNA, the less likely they are to be separated by a crossing-over event. In the case of male Drosophila there is complete absence of recombinant types due to absence of crossing over. This means that all of the genes that start out on a single chromosome, will end up on that same chromosome in their original configuration. In the absence of recombination, only parental phenotypes are expected. Linkage Genetic Linkage is the tendency of alleles, which are located closely together on a chromosome, to be inherited together during the process of meiosis in sexually reproducing organisms. During the process of meiosis, homologous chromosomes pair up, and can exchange corresponding sections of DNA. As a result, genes that were originally on the sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Complete-linkage Clustering
Complete-linkage clustering is one of several methods of agglomerative hierarchical clustering. At the beginning of the process, each element is in a cluster of its own. The clusters are then sequentially combined into larger clusters until all elements end up being in the same cluster. The method is also known as farthest neighbour clustering. The result of the clustering can be visualized as a dendrogram, which shows the sequence of cluster fusion and the distance at which each fusion took place. Clustering procedure At each step, the two clusters separated by the shortest distance are combined. The definition of 'shortest distance' is what differentiates between the different agglomerative clustering methods. In complete-linkage clustering, the link between two clusters contains all element pairs, and the distance between clusters equals the distance between those two elements (one in each cluster) that are farthest away from each other. The shortest of these links that r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swiss Centroid
Swiss may refer to: * the adjectival form of Switzerland *Swiss people Places *Swiss, Missouri * Swiss, North Carolina * Swiss, West Virginia *Swiss, Wisconsin Other uses * Swiss-system tournament, in various games and sports * Swiss International Air Lines **Swiss Global Air Lines, a subsidiary *Swissair, former national air line of Switzerland *.swiss alternative TLD for Switzerland See also *Swiss made, label for Swiss products *Swiss cheese (other) *Switzerland (other) *Languages of Switzerland, none of which are called "Swiss" *International Typographic Style, also known as Swiss Style, in graphic design *Schweizer (other), meaning Swiss in German *Schweitzer Schweitzer is a surname. Notable people with the surname include: * Albert Schweitzer, German theologian, musician, physician, and medical missionary, winner of the 1952 Nobel Peace Prize * Anton Schweitzer, opera composer * Brian Schweitzer, forme ..., a family name meaning Swiss in German * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Panic Disorder
Panic disorder is a mental disorder, mental and Abnormal behavior, behavioral disease#Disorder, disorder, specifically an anxiety disorder characterized by reoccurring unexpected panic attacks. Panic attacks are sudden periods of intense fear that may include palpitations, sweating, shaking, shortness of breath, numbness, or a feeling that something terrible is going to happen. The maximum degree of symptoms occurs within minutes. There may be ongoing worries about having further attacks and avoidance of places where attacks have occurred in the past. The cause of panic disorder is unknown. Panic disorder often runs in families. Risk factors include smoking, psychological stress, and a history of child abuse. Diagnosis involves ruling out other potential causes of anxiety including other mental disorders, medical conditions such as heart disease or hyperthyroidism, and drug use. Screening for the condition may be done using a Patient Health Questionnaire, questionnaire. Panic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centimorgan
In genetics, a centimorgan (abbreviated cM) or map unit (m.u.) is a unit for measuring genetic linkage. It is defined as the distance between chromosome positions (also termed loci or markers) for which the expected average number of intervening chromosomal crossovers in a single generation is 0.01. It is often used to infer distance along a chromosome. However, it is not a true physical distance. Relation to physical distance The number of base pairs to which it corresponds varies widely across the genome (different regions of a chromosome have different propensities towards crossover) and it also depends on whether the meiosis in which the crossing-over takes place is a part of oogenesis (formation of female gametes) or spermatogenesis (formation of male gametes). One centimorgan corresponds to about 1 million base pairs in humans on average. The relationship is only rough, as the physical chromosomal distance corresponding to one centimorgan varies from place to place in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reginald Punnett
Reginald Crundall Punnett FRS (; 20 June 1875 – 3 January 1967) was a British geneticist who co-founded, with William Bateson, the ''Journal of Genetics'' in 1910. Punnett is probably best remembered today as the creator of the Punnett square, a tool still used by biologists to predict the probability of possible genotypes of offspring. His ''Mendelism'' (1905) is sometimes said to have been the first textbook on genetics; it was probably the first popular science book to introduce genetics to the public. Life and work Reginald Punnett was born in 1875 in the town of Tonbridge in Kent, England. While recovering from a childhood bout of appendicitis, Punnett became acquainted with Jardine's Naturalist's Library and developed an interest in natural history. Punnett was educated at Clifton College. Attending Gonville and Caius College, Cambridge, Punnett earned a bachelor's degree in zoology in 1898 and a master's degree in 1901. Between these degrees he worked as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edith Rebecca Saunders
Edith Rebecca Saunders FLS (14 October 1865 – 6 June 1945) was a British geneticist and plant anatomist. Described by J. B. S. Haldane as the "Mother of British Plant Genetics", she played an active role in the re-discovery of Mendel's laws of heredity, the understanding of trait inheritance in plants, and was the first collaborator of the geneticist William Bateson. She also developed extensive work on flower anatomy, particularly focusing on the gynoecia, the female reproductive organs of flowers. Biography Saunders was born on 14 October 1865 in Brighton, England. She was educated first at Handsworth Ladies' College and in 1884 she entered the female-only Newnham College, Cambridge. There, she attended both Part I (in 1887) and II (in 1888) of the Natural Sciences Tripos. She continued to post-graduate research, and served as a demonstrator at the Balfour Biological Laboratory for Women between 1888 and 1890 (where students from Newnham and Girton colleges received pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Bateson
William Bateson (8 August 1861 – 8 February 1926) was an English biologist who was the first person to use the term genetics to describe the study of heredity, and the chief populariser of the ideas of Gregor Mendel following their rediscovery in 1900 by Hugo de Vries and Carl Correns. His 1894 book ''Materials for the Study of Variation'' was one of the earliest formulations of the new approach to genetics. Early life and education Bateson was born 1861 in Whitby on the Yorkshire coast, the son of William Henry Bateson, Master of St John's College, Cambridge. He was educated at Rugby School and at St John's College, where he graduated BA in 1883 with a first in natural sciences. Taking up embryology, he went to the United States to investigate the development of ''Balanoglossus'', a worm-like hemichordate which led to his interest in vertebrate origins. In 1883–4 he worked in the laboratory of William Keith Brooks, at the Chesapeake Zoölogical Laboratory in Hampton, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thomas Hunt Morgan
Thomas Hunt Morgan (September 25, 1866 – December 4, 1945) was an American evolutionary biologist, geneticist, embryologist, and science author who won the Nobel Prize in Physiology or Medicine in 1933 for discoveries elucidating the role that the chromosome plays in heredity. Morgan received his Ph.D. from Johns Hopkins University in zoology in 1890 and researched embryology during his tenure at Bryn Mawr. Following the rediscovery of Mendelian inheritance in 1900, Morgan began to study the genetic characteristics of the fruit fly ''Drosophila melanogaster''. In his famous Fly Room at Columbia University's Schermerhorn Hall, Morgan demonstrated that genes are carried on chromosomes and are the mechanical basis of heredity. These discoveries formed the basis of the modern science of genetics. During his distinguished career, Morgan wrote 22 books and 370 scientific papers. As a result of his work, ''Drosophila'' became a major model organism in contemporary genetics. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dendrogram
A dendrogram is a diagram representing a tree. This diagrammatic representation is frequently used in different contexts: * in hierarchical clustering, it illustrates the arrangement of the clusters produced by the corresponding analyses. * in computational biology, it shows the clustering of genes or samples, sometimes in the margins of heatmaps. * in phylogenetics, it displays the evolutionary relationships among various biological taxa. In this case, the dendrogram is also called a phylogenetic tree. The name ''dendrogram'' derives from the two ancient greek words (), meaning "tree", and (), meaning "drawing, mathematical figure". Clustering example For a clustering example, suppose that five taxa (a to e) have been clustered by UPGMA based on a matrix of genetic distances. The hierarchical clustering dendrogram would show a column of five nodes representing the initial data (here individual taxa), and the remaining nodes represent the clusters to which the dat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hierarchical Clustering
In data mining and statistics, hierarchical clustering (also called hierarchical cluster analysis or HCA) is a method of cluster analysis that seeks to build a hierarchy of clusters. Strategies for hierarchical clustering generally fall into two categories: * Agglomerative: This is a " bottom-up" approach: Each observation starts in its own cluster, and pairs of clusters are merged as one moves up the hierarchy. * Divisive: This is a "top-down" approach: All observations start in one cluster, and splits are performed recursively as one moves down the hierarchy. In general, the merges and splits are determined in a greedy manner. The results of hierarchical clustering are usually presented in a dendrogram. The standard algorithm for hierarchical agglomerative clustering (HAC) has a time complexity of \mathcal(n^3) and requires \Omega(n^2) memory, which makes it too slow for even medium data sets. However, for some special cases, optimal efficient agglomerative methods (of c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linkage Map
Genetic linkage is the tendency of DNA sequences that are close together on a chromosome to be inherited together during the meiosis phase of sexual reproduction. Two genetic markers that are physically near to each other are unlikely to be separated onto different chromatids during chromosomal crossover, and are therefore said to be more ''linked'' than markers that are far apart. In other words, the nearer two genes are on a chromosome, the lower the chance of recombination between them, and the more likely they are to be inherited together. Markers on different chromosomes are perfectly ''unlinked'', although the penetrance of potentially deleterious alleles may be influenced by the presence of other alleles, and these other alleles may be located on other chromosomes than that on which a particular potentially deleterious allele is located. Genetic linkage is the most prominent exception to Gregor Mendel's Law of Independent Assortment. The first experiment to demonstrate l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetics
Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar working in the 19th century in Brno, was the first to study genetics scientifically. Mendel studied "trait inheritance", patterns in the way traits are handed down from parents to offspring over time. He observed that organisms (pea plants) inherit traits by way of discrete "units of inheritance". This term, still used today, is a somewhat ambiguous definition of what is referred to as a gene. Trait inheritance and molecular inheritance mechanisms of genes are still primary principles of genetics in the 21st century, but modern genetics has expanded to study the function and behavior of genes. Gene structure and function, variation, and distribution are studied within the context of the cell, the organism (e.g. dominance), and within the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
