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Coefficient Of Coincidence
In genetics, the coefficient of coincidence (c.o.c.) is a measure of interference in the formation of chromosomal crossovers during meiosis. It is generally the case that, if there is a crossover at one spot on a chromosome, this decreases the likelihood of a crossover in a nearby spot. Griffiths AJF, Wessler SR, Lewontin RC, Carroll SB (2008) ''Introduction to Genetic Analysis''. New York: W. H. Freeman and Company. This is called interference. The coefficient of coincidence is typically calculated from recombination rates between three genes. If there are three genes in the order A B C, then we can determine how closely linked they are by frequency of recombination. Knowing the recombination rate between A and B and the recombination rate between B and C, we would naively expect the double recombination rate to be the product of these two rates. The coefficient of coincidence is calculated by dividing the ''actual'' frequency of double recombinants by this expected frequency ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosomal Crossover
Chromosomal crossover, or crossing over, is the exchange of genetic material during sexual reproduction between two homologous chromosomes' non-sister chromatids that results in recombinant chromosomes. It is one of the final phases of genetic recombination, which occurs in the ''pachytene'' stage of prophase I of meiosis during a process called synapsis. Synapsis begins before the synaptonemal complex develops and is not completed until near the end of prophase I. Crossover usually occurs when matching regions on matching chromosomes break and then reconnect to the other chromosome. Crossing over was described, in theory, by Thomas Hunt Morgan. He relied on the discovery of Frans Alfons Janssens who described the phenomenon in 1909 and had called it "chiasmatypie". The term '' chiasma'' is linked, if not identical, to chromosomal crossover. Morgan immediately saw the great importance of Janssens' cytological interpretation of chiasmata to the experimental results of hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meiosis
Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately result in four cells with only one copy of each chromosome ( haploid). Additionally, prior to the division, genetic material from the paternal and maternal copies of each chromosome is crossed over, creating new combinations of code on each chromosome. Later on, during fertilisation, the haploid cells produced by meiosis from a male and female will fuse to create a cell with two copies of each chromosome again, the zygote. Errors in meiosis resulting in aneuploidy (an abnormal number of chromosomes) are the leading known cause of miscarriage and the most frequent genetic cause of developmental disabilities. In meiosis, DNA replication is followed by two rounds of cell division to produce four daughter cells, each with half the number of chr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anthony J
Anthony or Antony is a masculine given name, derived from the ''Antonia (gens), Antonii'', a ''gens'' (Roman naming conventions, Roman family name) to which Mark Antony (''Marcus Antonius'') belonged. According to Plutarch, the Antonii gens were Heracleidae, being descendants of Anton, a son of Heracles. Anthony is an English language, English name that is in use in many countries. It has been among the top 100 most popular male baby names in the United States since the late 19th century and has been among the top 100 male baby names between 1998 and 2018 in many countries including Canada, Australia, England, Ireland and Scotland. Equivalents include ''Antonio'' in Italian, Spanish, Portuguese and Maltese; ''Αντώνιος'' in Greek; ''António'' or ''Antônio'' in Portuguese; ''Antoni'' in Catalan, Polish, and Slovene; ''Anton (given name), Anton'' in Dutch, Galician, German, Icelandic, Romanian, Russian, and Scandinavian languages; ''Antoine'' in French; ''Antal (given name ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Susan R
Susan is a feminine given name, from Persian "Susan" (lily flower), from Egyptian '' sšn'' and Coptic ''shoshen'' meaning "lotus flower", from Hebrew ''Shoshana'' meaning "lily" (in modern Hebrew this also means "rose" and a flower in general), from Greek ''Sousanna'', from Latin ''Susanna'', from Old French ''Susanne''. Variations * Susana (given name), Susanna, Susannah * Suzana, Suzanna, Suzannah * Susann, Suzan, Suzann * Susanne (given name), Suzanne * Susanne (given name) * Suzan (given name) * Suzanne * Suzette (given name) * Suzy (given name) * Zuzanna (given name) *Cezanne (Avant-garde) Nicknames Common nicknames for Susan include: * Sue, Susie, Susi (German), Suzi, Suzy, Suzie, Suze, Poosan, Sanna, Suzie, Sookie, Sukie, Sukey, Subo, Suus (Dutch), Shanti In other languages * fa, سوسن (Sousan, Susan) ** tg, Савсан (Savsan), tg, Сӯсан (Sūsan) * ku, Sosna,Swesne * ar, سوسن (Sawsan) * hy, Շուշան (Šušan) * (Sushan) * S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richard Lewontin
Richard Charles Lewontin (March 29, 1929 – July 4, 2021) was an American evolutionary biologist, mathematician, geneticist, and social commentator. A leader in developing the mathematical basis of population genetics and evolutionary theory, he pioneered the application of techniques from molecular biology, such as gel electrophoresis, to questions of genetic variation and evolution. In a pair of seminal 1966 papers co-authored with J. L. Hubby in the journal ''Genetics'', Lewontin helped set the stage for the modern field of molecular evolution. In 1979 he and Stephen Jay Gould introduced the term "spandrel" into evolutionary theory. From 1973 to 1998, he held an endowed chair in zoology and biology at Harvard University, and from 2003 until his death in 2021 he was a research professor there. Lewontin opposed genetic determinism. Early life and education Lewontin was born in New York City, to parents descended from late 19th-century Ashkenazi Jewish immigrants. His father ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sean B
Sean, also spelled Seán or Séan in Irish English, is a male given name of Irish origin. It comes from the Irish versions of the Biblical Hebrew name ''Yohanan'' (), Seán (anglicized as ''Shaun/Shawn/ Shon'') and Séan (Ulster variant; anglicized ''Shane/Shayne''), rendered ''John'' in English and Johannes/Johann/Johan in other Germanic languages. The Norman French ''Jehan'' (see ''Jean'') is another version. For notable people named Sean, refer to List of people named Sean. Origin The name was adopted into the Irish language most likely from ''Jean'', the French variant of the Hebrew name ''Yohanan''. As Gaelic has no letter (derived from ; English also lacked until the late 17th Century, with ''John'' previously been spelt ''Iohn'') so it is substituted by , as was the normal Gaelic practice for adapting Biblical names that contain in other languages (''Sine''/''Siobhàn'' for ''Joan/Jane/Anne/Anna''; ''Seonaid''/''Sinéad'' for ''Janet''; ''Seumas''/''Séamus'' for ''Jam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Linkage
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 li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Product (mathematics)
In mathematics, a product is the result of multiplication, or an expression that identifies objects (numbers or variables) to be multiplied, called ''factors''. For example, 30 is the product of 6 and 5 (the result of multiplication), and x\cdot (2+x) is the product of x and (2+x) (indicating that the two factors should be multiplied together). The order in which real or complex numbers are multiplied has no bearing on the product; this is known as the ''commutative law'' of multiplication. When matrices or members of various other associative algebras are multiplied, the product usually depends on the order of the factors. Matrix multiplication, for example, is non-commutative, and so is multiplication in other algebras in general as well. There are many different kinds of products in mathematics: besides being able to multiply just numbers, polynomials or matrices, one can also define products on many different algebraic structures. Product of two numbers Product of a seque ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila Melanogaster
''Drosophila melanogaster'' is a species of fly (the taxonomic order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the "vinegar fly" or "pomace fly". Starting with Charles W. Woodworth's 1901 proposal of the use of this species as a model organism, ''D. melanogaster'' continues to be widely used for biological research in genetics, physiology, microbial pathogenesis, and life history evolution. As of 2017, five Nobel Prizes have been awarded to drosophilists for their work using the insect. ''D. melanogaster'' is typically used in research owing to its rapid life cycle, relatively simple genetics with only four pairs of chromosomes, and large number of offspring per generation. It was originally an African species, with all non-African lineages having a common origin. Its geographic range includes all continents, including islands. ''D. melanogaster'' is a common pest in homes, restaurants, and othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genotype
The genotype of an organism is its complete set of genetic material. Genotype can also be used to refer to the alleles or variants an individual carries in a particular gene or genetic location. The number of alleles an individual can have in a specific gene depends on the number of copies of each chromosome found in that species, also referred to as ploidy. In diploid species like humans, two full sets of chromosomes are present, meaning each individual has two alleles for any given gene. If both alleles are the same, the genotype is referred to as homozygous. If the alleles are different, the genotype is referred to as heterozygous. Genotype contributes to phenotype, the observable traits and characteristics in an individual or organism. The degree to which genotype affects phenotype depends on the trait. For example, the petal color in a pea plant is exclusively determined by genotype. The petals can be purple or white depending on the alleles present in the pea plant. Howev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenotype
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological properties, its behavior, and the products of behavior. An organism's phenotype results from two basic factors: the expression of an organism's genetic code, or its genotype, and the influence of environmental factors. Both factors may interact, further affecting phenotype. When two or more clearly different phenotypes exist in the same population of a species, the species is called polymorphic. A well-documented example of polymorphism is Labrador Retriever coloring; while the coat color depends on many genes, it is clearly seen in the environment as yellow, black, and brown. Richard Dawkins in 1978 and then again in his 1982 book ''The Extended Phenotype'' suggested that one can regard bird nests and other built structures such as cad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
