August Weismann

Friedrich Leopold August Weismann (*January 17, 1834 in Frankfurt am Main; † November 5, 1914 in Freiburg im Breisgau) was a German Biologist. Ernst Mayr ranks him the second most notable evolutionary theorist of the 19th century, after Charles Darwin. Weismann advocated the germ plasm theory, stating that a multicellular organism consists of germ cells that pass on hereditary information, and somatic cells that perform body functions. The germ cells are not affected by anything the body learns or any ability it acquires duri ...

Including:

• August Weismann - Life
• August Weismann - Youth and studies
• August Weismann - Professional life
• August Weismann - Contributions to evolutionary biology
• August Weismann - 1868-1881/82
• August Weismann - 1882-1895
• August Weismann - 1896-1910
• August Weismann - Some written work
• August Weismann - Literature

Read more here: » August Weismann: Encyclopedia - August Weismann

At the beginning of Weismann's preoccupation with evolutionary theory is his grappling with Christian creationism as a possible alternative. In his work Über die Berechtigung der Darwin'schen Theorie (On the justification of the Darwinian theory) he compares creationism and evolutionary theory, concluding that many biological facts can be seamlessly accommodated within evolutionary ...

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August Weismann, August Weismann - Life, August Weismann - Youth and studies, August Weismann - Professional life, August Weismann - Contributions to evolutionary biology, August Weismann - 1868-1881/82, August Weismann - 1882-1895, August Weismann - 1896-1910, August Weismann - Some written work, August Weismann - Literature

Read more here: » August Weismann: Encyclopedia II - August Weismann - Contributions to evolutionary biology

Heredity (the adjective is hereditary) is the transfer of characteristics from parent to offspring, either through their genes or through the social institution called inheritance (for example, a title of nobility is passed from individual to individual according to relevant customs and/or laws). Heredity - Biology. In biology, heredity refers to the transference of biological characteristics from a parent organism to offspring, and is practically a synonym for genetics, as genes ...

Including:

• Heredity - Biology
• Heredity - History of heredity in biology
• Heredity - Sociology

Read more here: » Heredity: Encyclopedia - Heredity

List of biologists - Ba-Bi. Churchill Babington (1831-1881), British archaeologist and conchologist John Bachman (1790-1874), American naturalist Curt Backeberg (1894-1966), German botanist (abbr. in botany: Backeb.) Karl Ernst von Baer (1792-1876), embryology Liberty Hyde Bailey (1858-1954),American botanist (abbr. in botany : L.H.Bailey) Spencer Fullerton Baird, (1823-1887), birds and mammals John Hutton Balfour (1808-1884), Scottish botanist (abb ...

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List of biologists, List of biologists - A, List of biologists - B, List of biologists - Ba-Bi, List of biologists - Bl-Bu, List of biologists - C, List of biologists - D, List of biologists - E, List of biologists - F, List of biologists - G, List of biologists - H, List of biologists - I, List of biologists - J, List of biologists - K, List of biologists - L, List of biologists - M, List of biologists - Ma-Mi, List of biologists - Mo-Mu, List of biologists - N, List of biologists - O, List of biologists - P, List of biologists - Q, List of biologists - R, List of biologists - S, List of biologists - Sa-So, List of biologists - Sp-Sy, List of biologists - T, List of biologists - U, List of biologists - V, List of biologists - W, List of biologists - X, List of biologists - Y, List of biologists - Z

Read more here: » List of biologists: Encyclopedia II - List of biologists - B

Because meiosis is a "one-way" process, it cannot be said to engage in a cell cycle that mitosis does. However, the preparatory steps that lead up to meiosis are identical in pattern and name to the interphase of the mitotic cell cycle. Interphase is divided into three phases: Growth 1 (G1) phase: Characterized by increasing cell size from accelerated manufacture of organelles, proteins, and other cellular matter. Synthesis (S) phase: The genetic material is replicated. Growth 2 (G2) phase: ...

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Meiosis, Meiosis - History, Meiosis - Occurrence of meiosis in eukaryotic life cycles, Meiosis - Chromosome segregation in meiosis, Meiosis - Process, Meiosis - Meiosis I, Meiosis - Meiosis II, Meiosis - Significance of meiosis, Meiosis - Nondisjunction, Meiosis - Meiosis in humans

Read more here: » Meiosis: Encyclopedia II - Meiosis - Process

Following the Voyage of the Beagle, Charles Darwin had at his disposal a considerable collection of specimens and on 29 October 1836 he was introduced by Charles Lyell to Owen, who agreed to work on fossil bones collected in South America. Owen's subsequent revelations that extinct giant creatures were rodents and sloths showed that they were related to current species in the same locality, rather than being relatives of similarly sized creatures in Africa as Darwin had originally thought. Thi ...

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Richard Owen, Richard Owen - Early life and career, Richard Owen - Work on invertebrates, Richard Owen - Work on fish reptiles and birds, Richard Owen - Work on mammals, Richard Owen - Owen and Darwin's theory of evolution, Richard Owen - Owen's legacy

Read more here: » Richard Owen: Encyclopedia II - Richard Owen - Owen and Darwin's theory of evolution

After publication of the Origin of Species, Darwin became interested in the explanations of animal and plant mechanisms which confer advantages to the individuals within a species. Much important work was done by Fritz Muller (Für Darwin), by Herman Muller (Fertilization of Plants by Insects), by August Weismann (memoirs translated by Meldola) by Edward B. Poulton (see his addresses and memoirs in the Transactions of the Entomological Society and elsewhere), and by Abbot Thayer (Co ...

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History of zoology post-Darwin, History of zoology post-Darwin - Early 20th century work, History of zoology post-Darwin - Mendel and zoology, History of zoology post-Darwin - Congenital variation, History of zoology post-Darwin - Educability, History of zoology post-Darwin - Transmission, History of zoology post-Darwin - Record of the past

Read more here: » History of zoology post-Darwin: Encyclopedia II - History of zoology post-Darwin - Early 20th century work

Lamarck was born in Bazentin-le-Petit, Picardy on August 1, 1744. Born into poor nobility (hence chevalier - knight), Lamarck served in the army before becoming interested in natural history and writing a multi-volume flora of France. This caught the attention of Georges-Louis Leclerc, Comte de Buffon who arranged for him to be appointed to the Muséum National d'Histoire Naturelle in Paris. After years working on plants, Lamarck was appointed curator of invertebrates — another term he coined. He began a series of public lect ...

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Jean-Baptiste Lamarck, Jean-Baptiste Lamarck - Biography, Jean-Baptiste Lamarck - Legacy, Jean-Baptiste Lamarck - Selective Bibliography and online works

Read more here: » Jean-Baptiste Lamarck: Encyclopedia II - Jean-Baptiste Lamarck - Biography

Evolutionary biology as an academic discipline in its own right emerged as a result of the modern evolutionary synthesis in the 1930s and 1940s. It was not until the 1970s and 1980s, however, that a significant number of universities had departments that specifically included the term evolutionary biology in their titles. In the United States, as a result of the rapid growth of molecular and cell biology, many universities have split (or aggregated) their biology departments into molecular and cell biology-style departments and ...

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Evolutionary biology, Evolutionary biology - History, Evolutionary biology - Notable evolutionary biologists, Evolutionary biology - Bibliography, Evolutionary biology - Textbooks, Evolutionary biology - Notable monographs and other works, Evolutionary biology - Topics in evolutionary biology

Read more here: » Evolutionary biology: Encyclopedia II - Evolutionary biology - History

List of Germans - Chancellors of Germany before 2nd World War. Gustav Stresemann, (1878-1929), chancellor and statesman of the Weimar Republic (DVP) Joseph Wirth, (1879-1956), Chancellor of the Weimar Period (Centre) Franz von Papen (1879-1969), chancellor and politician of the Weimar Republic Philipp Scheidemann, (1865-1939), chancellor in the Weimar period (SPD) Kurt von Schleicher - general and chancellor in the Weimar period Georg Michaelis, (1857-1936), Impe ...

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List of Germans, List of Germans - Actors, List of Germans - Artists, List of Germans - Composers, List of Germans - Filmmakers, List of Germans - Royalty, List of Germans - Musicians and singers, List of Germans - Philosophers, List of Germans - Politicians, List of Germans - Chancellors of Germany before 2nd World War, List of Germans - Chancellors of Germany after 2nd World War, List of Germans - Presidents of Germany, List of Germans - Politicians in East Germany, List of Germans - Personalities of the Nazi Party and Regime, List of Germans - Scientists and engineers, List of Germans - Sportspersons, List of Germans - Theologians, List of Germans - Writers, List of Germans - Others

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In the late 20th century there have been criticisms of an impermeable Weismann barrier. These criticisms are all centered around the activities of an enzyme called reverse transcriptase. Evidence has begun to mount for horizontal gene transfer. Different species appear to be swapping genes through the activities of retroviruses. Retro-viruses are able to transfer genes between species because they reproduce by integrating their code into the genome of the host and they often move nearby code in the infected cell as well. Seeing as the ...

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Weismann barrier, Weismann barrier - History, Weismann barrier - Recent criticism

Read more here: » Weismann barrier: Encyclopedia II - Weismann barrier - Recent criticism

Main article: History of evolutionary thought Evolutionary biology as an academic discipline in its own right emerged as a result of the modern evolutionary synthesis in the 1930s and 1940s. It was not until the 1970s and 1980s, however, that a significant number of universities had departments that specifically included the term evolutionary biology in their titles. In the United States, as a result of the rapid growth of molecular and cell biology, many universities have split (or aggregated) their biology departments ...

See also:

Evolutionary biology, Evolutionary biology - History, Evolutionary biology - Notable evolutionary biologists, Evolutionary biology - Bibliography, Evolutionary biology - Textbooks, Evolutionary biology - Notable monographs and other works, Evolutionary biology - Topics in evolutionary biology

Read more here: » Evolutionary biology: Encyclopedia II - Evolutionary biology - History

The gene-centric view of evolution is the logical extension of the theory of natural selection proposed by Charles Darwin and Alfred Russell Wallace in the light of the discoveries about the mechanisms of inheritance and development. Gregor Mendel's particulate inheritance theory, August Weismann's continuity of the germ plasm, and Francis Crick's central dogma of molecular biology identified genes codified in DNA molecules as (1) the persistent entities that are transmitted th ...

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Gene-centered view of evolution, Gene-centered view of evolution - Historic, Gene-centered view of evolution - A defense, Gene-centered view of evolution - Genetic determinism, Gene-centered view of evolution - Adaptation, Gene-centered view of evolution - Conclusion, Gene-centered view of evolution - Bibliography

Read more here: » Gene-centered view of evolution: Encyclopedia II - Gene-centered view of evolution - Historic

In biology, heredity refers to the transference of biological characteristics from a parent organism to offspring, and is practically a synonym for genetics, as genes are now recognized as the carriers of biological information. In humans, defining which characteristics of a final person are due to heredity and which are due to environmental influences is often a site of controversy (the nature versus nurture debate), especially regarding intelligence and race. Heredity - Hi ...

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Heredity, Heredity - Biology, Heredity - History of heredity in biology, Heredity - Sociology

Read more here: » Heredity: Encyclopedia II - Heredity - Biology

His defenders believe he is unfairly vilified today. They note that he believed in organic evolution at a time when there was no theoretical framework to explain evolution. He also argued that function precedes form, an issue of some contention among evolutionary theorists at the time. On the other hand, the inheritance of acquired characteristics is now widely rejected. August Weismann disproved the theory by cutting the tails off mice, demonstrating that the injury was not passed on to the offspring. Jews and other religious groups have be ...

See also:

Jean-Baptiste Lamarck, Jean-Baptiste Lamarck - Biography, Jean-Baptiste Lamarck - Legacy, Jean-Baptiste Lamarck - Selective Bibliography and online works

Read more here: » Jean-Baptiste Lamarck: Encyclopedia II - Jean-Baptiste Lamarck - Legacy

A diploid cell contains a full set of chromosome pairs, each pair containing one chromosome from each parent. These chromosome pairs are called homologous chromosomes. Homologous chromosomes need not be genetically identical. For example, one particular locus (location) on one of the father's chromosomes may code for green eyes, while the same locus on the mother's chromosome may code for brown eyes. This genetic var ...

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Meiosis, Meiosis - History, Meiosis - Occurrence of meiosis in eukaryotic life cycles, Meiosis - Chromosome segregation in meiosis, Meiosis - Process, Meiosis - Meiosis I, Meiosis - Meiosis II, Meiosis - Significance of meiosis, Meiosis - Nondisjunction, Meiosis - Meiosis in humans

Read more here: » Meiosis: Encyclopedia II - Meiosis - Chromosome segregation in meiosis

The normal separation of chromosomes in Meiosis I or sister chromatids in meiosis II is termed disjunction. When the separation is not normal, it is called nondisjunction. This results in the production of gametes which have either more or less of the usual amount of genetic material, and is a common mechanism for trisomy or monosomy. Nondisjunction can occur in the meiosis I or meiosis II phases of ...

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Meiosis, Meiosis - History, Meiosis - Occurrence of meiosis in eukaryotic life cycles, Meiosis - Chromosome segregation in meiosis, Meiosis - Process, Meiosis - Meiosis I, Meiosis - Meiosis II, Meiosis - Significance of meiosis, Meiosis - Nondisjunction, Meiosis - Meiosis in humans

Read more here: » Meiosis: Encyclopedia II - Meiosis - Nondisjunction

Meiosis facilitates stable sexual reproduction. Without the halving of ploidy, or chromosome count, fertilization would result in zygotes that have twice the number of chromosomes than the zygotes from the previous generation. Successive generations would have an exponential increase in chromosome count, resulting in an unwieldy genome that would cripple the reproductive fitness of the species. Polyploidy, the state of having three or more sets of chromosomes, also r ...

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Meiosis, Meiosis - History, Meiosis - Occurrence of meiosis in eukaryotic life cycles, Meiosis - Chromosome segregation in meiosis, Meiosis - Process, Meiosis - Meiosis I, Meiosis - Meiosis II, Meiosis - Significance of meiosis, Meiosis - Nondisjunction, Meiosis - Meiosis in humans

Read more here: » Meiosis: Encyclopedia II - Meiosis - Significance of meiosis

In females, meiosis occurs in precursor cells known as oogonia that divide twice into oocytes. These stem cells stop at the diplotene stage of meiosis I and lay dormant within a protective shell of somatic cells called the follicle. Follicles begin growth at a steady pace in a process known as folliculogenesis, and a small number enter the menstrual cycle. Menstruated oocytes continue meiosis I and arrest at meiosis II until fertilization. The proce ...

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Meiosis, Meiosis - History, Meiosis - Occurrence of meiosis in eukaryotic life cycles, Meiosis - Chromosome segregation in meiosis, Meiosis - Process, Meiosis - Meiosis I, Meiosis - Meiosis II, Meiosis - Significance of meiosis, Meiosis - Nondisjunction, Meiosis - Meiosis in humans

Read more here: » Meiosis: Encyclopedia II - Meiosis - Meiosis in humans

Meiosis occurs in all eukaryotic life cycles involving sexual reproduction, comprising of the constant cyclical process of meiosis and fertilization. This takes place alongside normal mitotic cell division. In multicellular organisms, there is an intermediary step between the diploid and haploid transition where the organism grows. The organism will then produce the germ cells that continue in the life cycle. The rest of the cells, called somatic cells, function within the organism and will die with it. The organism phase of the life ...

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Meiosis, Meiosis - History, Meiosis - Occurrence of meiosis in eukaryotic life cycles, Meiosis - Chromosome segregation in meiosis, Meiosis - Process, Meiosis - Meiosis I, Meiosis - Meiosis II, Meiosis - Significance of meiosis, Meiosis - Nondisjunction, Meiosis - Meiosis in humans

Read more here: » Meiosis: Encyclopedia II - Meiosis - Occurrence of meiosis in eukaryotic life cycles