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Chromosomes (human)
A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are the histones. These proteins, aided by chaperone proteins, bind to and condense the DNA molecule to maintain its integrity. These chromosomes display a complex three-dimensional structure, which plays a significant role in transcriptional regulation. Chromosomes are normally visible under a light microscope only during the metaphase of cell division (where all chromosomes are aligned in the center of the cell in their condensed form). Before this happens, each chromosome is duplicated (S phase), and both copies are joined by a centromere, resulting either in an X-shaped structure (pictured above), if the centromere is located equatorially, or a two-arm structure, if the centromere is located distally. The joined copies are now called sist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome
A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are the histones. These proteins, aided by chaperone proteins, bind to and condense the DNA molecule to maintain its integrity. These chromosomes display a complex three-dimensional structure, which plays a significant role in transcriptional regulation. Chromosomes are normally visible under a light microscope only during the metaphase of cell division (where all chromosomes are aligned in the center of the cell in their condensed form). Before this happens, each chromosome is duplicated ( S phase), and both copies are joined by a centromere, resulting either in an X-shaped structure (pictured above), if the centromere is located equatorially, or a two-arm structure, if the centromere is located distally. The joined copies are now called si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexual Reproduction
Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete ( haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to produce a zygote that develops into an organism composed of cells with two sets of chromosomes ( diploid). This is typical in animals, though the number of chromosome sets and how that number changes in sexual reproduction varies, especially among plants, fungi, and other eukaryotes. Sexual reproduction is the most common life cycle in multicellular eukaryotes, such as animals, fungi and plants. Sexual reproduction also occurs in some unicellular eukaryotes. Sexual reproduction does not occur in prokaryotes, unicellular organisms without cell nuclei, such bacteria and archaea. However, some process in bacteria may be considered analogous to sexual reproduction in that they incorporate new genetic information, including bacterial conjugation, transformatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rudolf Virchow
Rudolf Ludwig Carl Virchow (; or ; 13 October 18215 September 1902) was a German physician, anthropologist, pathologist, prehistorian, biologist, writer, editor, and politician. He is known as "the father of modern pathology" and as the founder of social medicine, and to his colleagues, the "Pope of medicine". Virchow studied medicine at the Friedrich Wilhelm University under Johannes Peter Müller. While working at the Charité hospital, his investigation of the 1847–1848 typhus epidemic in Upper Silesia laid the foundation for public health in Germany, and paved his political and social careers. From it, he coined a well known aphorism: "Medicine is a social science, and politics is nothing else but medicine on a large scale". His participation in the Revolution of 1848 led to his expulsion from Charité the next year. He then published a newspaper ''Die Medizinische Reform'' (''The Medical Reform''). He took the first Chair of Pathological Anatomy at the University of Wü ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Matthias Jakob Schleiden
Matthias Jakob Schleiden (; 5 April 1804 – 23 June 1881) was a German botanist and co-founder of cell theory, along with Theodor Schwann and Rudolf Virchow. Career Matthias Jakob Schleiden was born in Hamburg. on 5 April 1804. His father was the municipal physician of Hamburg. Schleiden pursued legal studies graduating in 1827. He then established a legal practice but after a period of emotional depression and attempted suicide, he changed professions. He studied natural science at the University of Göttingen in Göttingen, Germany, but transferred to the University of Berlin in 1835 to study plants. Johann Horkel, Schleiden's uncle, encouraged him to study plant embryology. He soon developed his love for botany and cats into a full-time pursuit. Schleiden preferred to study plant structure under the microscope. As a professor of botany at the University of Jena, he wrote ''Contributions to our Knowledge of Phytogenesis'' (1838), in which he stated that all plants are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theodor Boveri
Theodor Heinrich Boveri (12 October 1862 – 15 October 1915) was a German zoologist, comparative anatomist and co-founder of modern cytology. He was notable for the first hypothesis regarding cellular processes that cause cancer, and for describing ''chromatin diminution in nematodes''. Boveri was married to the American biologist Marcella O'Grady (1863–1950). Their daughter Margret Boveri (1900–1975) became one of the best-known journalists in post-World War II Germany. Work Using an optical microscope, Boveri examined the processes involved in the fertilization of the animal egg cell; his favorite research objects were the nematode ''Parascaris'' and sea urchins. Boveri's work with sea urchins showed that it was necessary to have all chromosomes present in order for proper embryonic development to take place. This discovery was an important part of the Boveri–Sutton chromosome theory. He also discovered, in 1888, the importance of the centrosome for the formation of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Walter Sutton
Walter Stanborough Sutton (April 5, 1877 – November 10, 1916) was an American geneticist and physician whose most significant contribution to present-day biology was his theory that the Mendelian laws of inheritance could be applied to chromosomes at the cellular level of living organisms. This is now known as the Boveri-Sutton chromosome theory. Early life Sutton was born in Utica, New York, and was raised on a farm as the fifth of seven sons to Judge William B. Sutton and his wife, Agnes Black Sutton, in Russell, Kansas. On the farm, he developed a mechanical aptitude by maintaining and repairing farm equipment, an aptitude that proved helpful later as he worked on oil drilling rigs and with medical instrumentation. University of Kansas After graduating high school in Russell, he enrolled at the University of Kansas in engineering in 1896. Following the death of his younger brother (John) from typhus in 1897, Sutton switched his major to biology with an interest in medic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Walther Flemming
Walther Flemming (21 April 1843 – 4 August 1905) was a German biologist and a founder of cytogenetics. He was born in Sachsenberg (now part of Schwerin) as the fifth child and only son of the psychiatrist Carl Friedrich Flemming (1799–1880) and his second wife, Auguste Winter. He graduated from the ''Gymnasium der Residenzstadt'', where one of his colleagues and lifelong friends was writer Heinrich Seidel. Career Flemming trained in medicine at the University of Prague, graduating in 1868. Afterwards, he served in 1870–71 as a military physician in the Franco-Prussian War. From 1873 to 1876 he worked as a teacher at the University of Prague. In 1876 he accepted a post as a professor of anatomy at the University of Kiel. He became the director of the Anatomical Institute and stayed there until his death. With the use of aniline dyes he was able to find a structure which strongly absorbed basophilic dyes, which he named chromatin. He identified that chromatin was corre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heinrich Wilhelm Gottfried Von Waldeyer-Hartz
Heinrich Wilhelm Gottfried von Waldeyer-Hartz (6 October 1836 – 23 January 1921) was a German anatomist, known for summarizing neuron theory and for naming the chromosome. He is also remembered by anatomical structures of the human body which were named after him: Waldeyer's tonsillar ring (the lymphoid tissue ring of the naso- and oropharynx) and Waldeyer's glands (of the eyelids). Contribution to neuron theory Waldeyer's name is associated in neuroscience with the " neuron theory", and for coining the term "neuron" to describe the basic structural unit of the nervous system. Waldeyer synthesized the discoveries by neuroanatomists (and later Nobel Prize winners) Camillo Golgi (1843–1926) and Santiago Ramón y Cajal (1852–1934), who had used the silver nitrate method of staining nerve tissue (Golgi's method), to formulate widely cited reviews of the theory. Waldeyer learned Spanish in order to absorb Cajal's detailed studies using Golgi's method and became his friend, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greek Language
Greek ( el, label=Modern Greek, Ελληνικά, Elliniká, ; grc, Ἑλληνική, Hellēnikḗ) is an independent branch of the Indo-European family of languages, native to Greece, Cyprus, southern Italy (Calabria and Salento), southern Albania, and other regions of the Balkans, the Black Sea coast, Asia Minor, and the Eastern Mediterranean. It has the longest documented history of any Indo-European language, spanning at least 3,400 years of written records. Its writing system is the Greek alphabet, which has been used for approximately 2,800 years; previously, Greek was recorded in writing systems such as Linear B and the Cypriot syllabary. The alphabet arose from the Phoenician script and was in turn the basis of the Latin, Cyrillic, Armenian, Coptic, Gothic, and many other writing systems. The Greek language holds a very important place in the history of the Western world. Beginning with the epics of Homer, ancient Greek literature includes many works of lasting impo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromatin
Chromatin is a complex of DNA and protein found in eukaryotic cells. The primary function is to package long DNA molecules into more compact, denser structures. This prevents the strands from becoming tangled and also plays important roles in reinforcing the DNA during cell division, preventing DNA damage, and regulating gene expression and DNA replication. During mitosis and meiosis, chromatin facilitates proper segregation of the chromosomes in anaphase; the characteristic shapes of chromosomes visible during this stage are the result of DNA being coiled into highly condensed chromatin. The primary protein components of chromatin are histones. An octamer of two sets of four histone cores (Histone H2A, Histone H2B, Histone H3, and Histone H4) bind to DNA and function as "anchors" around which the strands are wound.Maeshima, K., Ide, S., & Babokhov, M. (2019). Dynamic chromatin organization without the 30-nm fiber. ''Current opinion in cell biology, 58,'' 95–104. https://doi.o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cancer
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal bleeding, prolonged cough, unexplained weight loss, and a change in bowel movements. While these symptoms may indicate cancer, they can also have other causes. Over 100 types of cancers affect humans. Tobacco use is the cause of about 22% of cancer deaths. Another 10% are due to obesity, poor diet, lack of physical activity or excessive drinking of alcohol. Other factors include certain infections, exposure to ionizing radiation, and environmental pollutants. In the developing world, 15% of cancers are due to infections such as ''Helicobacter pylori'', hepatitis B, hepatitis C, human papillomavirus infection, Epstein–Barr virus and human immunodeficiency virus (HIV). These factors act, at least partly, by changing the genes of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
