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Eye Color
Eye color is a polygene, polygenic phenotypic trait determined by two factors: the pigmentation of the eye's Iris (anatomy), iris and the frequency-dependence of the scattering of light by the Turbidity, turbid medium in the Stroma of iris, stroma of the iris. In humans, the pigmentation of the Iris (anatomy), iris varies from light brown to black, depending on the concentration of melanin in the iris pigment epithelium (located on the back of the iris), the melanin content within the iris stroma (located at the front of the iris), and the cellular density of the stroma. The appearance of blue, green, and hazel eyes results from the Tyndall effect, Tyndall scattering of light in the stroma, a phenomenon similar to Rayleigh scattering which accounts for the blue sky. Neither blue nor green pigments are present in the human iris or vitreous humour. This is an example of structural color, which depends on the lighting conditions, especially for lighter-colored eyes. The brightly c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenotypic
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology (physical form and structure), its developmental processes, its biochemical and physiological properties, and its behavior. An organism's phenotype results from two basic factors: the expression of an organism's genetic code (its genotype) and the influence of environmental factors. Both factors may interact, further affecting the 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 again in his 1982 book '' The Extended Phenotype'' suggested that one can regard bird nests and other built structures such as caddisfly larva cases and beaver dams ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome 15
Chromosome 15 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 15 spans about 99.7 million base pairs (the building material of DNA) and represents between 3% and 3.5% of the total DNA in cells. Chromosome 15 is an acrocentric chromosome, with a very small short arm (the "p" arm, for "petite"), which contains few protein coding genes among its 19 million base pairs. It has a larger long arm (the "q" arm) that is gene rich, spanning about 83 million base pairs. The human leukocyte antigen gene for β2-microglobulin is found on chromosome 15, as well as the FBN1 gene, coding for both fibrillin-1 (a protein critical to the proper functioning of connective tissue), and asprosin (a small protein produced from part of the transcribed FBN1 gene mRNA), which is involved in fat metabolism. Genes Number of genes The following are some of the gene count estimates of human chromosome 15. Because researchers use different appr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Recent African Origin Of Modern Humans
The recent African origin of modern humans or the "Out of Africa" theory (OOA) is the most widely accepted paleoanthropology, paleo-anthropological model of the geographic origin and Early human migrations, early migration of early modern human, anatomically modern humans (''Human, Homo sapiens''). It follows the early expansions of hominins out of Africa, accomplished by ''Homo erectus'' and then ''Neanderthal, Homo neanderthalensis''. The model proposes a "monogenism, single origin" of ''Human, Homo sapiens'' in the taxonomic sense, precluding parallel evolution in other regions of traits considered anatomically modern humans, anatomically modern, but not precluding multiple Archaic human admixture with modern humans, admixture between ''H. sapiens'' and archaic humans in Europe and Asia. ''H. sapiens'' most likely developed in the Horn of Africa between 300,000 and 200,000 years ago, although an alternative hypothesis argues that diverse morphological features of ''H. sap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Near East
The Near East () is a transcontinental region around the Eastern Mediterranean encompassing the historical Fertile Crescent, the Levant, Anatolia, Egypt, Mesopotamia, and coastal areas of the Arabian Peninsula. The term was invented in the 20th century by modern Western geographers and was originally applied to the Ottoman Empire, but today has varying definitions within different academic circles. The term ''Near East'' was used in conjunction with the ''Middle East'' and the ''Far East'' (China and beyond), together known as the "three Easts"; it was a separate term from the ''Middle East'' during earlier times and official British usage. As of 2024, both terms are used interchangeably by politicians and news reporters to refer to the same region. ''Near East'' and ''Middle East'' are both Eurocentrism, Eurocentric terms. According to the National Geographic Society, the terms ''Near East'' and ''Middle East'' denote the same territories and are "generally accepted as comprisin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient DNA
Ancient DNA (aDNA) is DNA isolated from ancient sources (typically Biological specimen, specimens, but also environmental DNA). Due to degradation processes (including Crosslinking of DNA, cross-linking, deamination and DNA fragmentation, fragmentation) ancient DNA is more degraded in comparison with present-day genetic material. Genetic material has been recovered from paleo/archaeological and historical skeletal material, Mummy, mummified tissues, archival collections of non-frozen medical specimens, preserved plant remains, ice and from permafrost cores, marine and lake sediments and Excavation (archaeology), excavation dirt. Even under the best preservation conditions, there is an upper boundary of 0.4–1.5 million years for a sample to contain sufficient DNA for sequencing technologies. The oldest DNA sequenced from physical specimens are from mammoth molars in Siberia over 1 million years old. In 2022, two-million-year-old genetic material was recovered from sediments in G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Estrogen
Estrogen (also spelled oestrogen in British English; see spelling differences) is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal activity: estrone (E1), estradiol (E2), and estriol (E3). Estradiol, an estrane, is the most potent and prevalent. Another estrogen called estetrol (E4) is produced only during pregnancy. Estrogens are synthesized in all vertebrates and some insects. Quantitatively, estrogens circulate at lower levels than androgens in both men and women. While estrogen levels are significantly lower in males than in females, estrogens nevertheless have important physiological roles in males. Like all steroid hormones, estrogens readily diffuse across the cell membrane. Once inside the cell, they bind to and activate estrogen receptors (ERs) which in turn modulate the expression of many ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Current Biology
''Current Biology'' is a biweekly peer-reviewed scientific journal that covers all areas of biology, especially molecular biology, cell biology, genetics, neurobiology, ecology, and evolutionary biology. The journal includes research articles, various types of review articles, as well as an editorial magazine section. The journal was established in 1991 by the Current Science group, was acquired by Elsevier in 1998, and has since 2001 been part of Cell Press, a subdivision of Elsevier. According to '' Journal Citation Reports'', the journal has a 2020 impact factor of 10.834. It was categorized as a "high impact journal" by the Superfund Research Program. References External links * Biology journals English-language journals Cell Press academic journals Academic journals established in 1991 Biweekly journals {{biology-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New Scientist
''New Scientist'' is a popular science magazine covering all aspects of science and technology. Based in London, it publishes weekly English-language editions in the United Kingdom, the United States and Australia. An editorially separate organisation publishes a monthly Dutch-language edition. First published on 22 November 1956, ''New Scientist'' has been available in online form since 1996. Sold in retail outlets (paper edition) and on subscription (paper and/or online), the magazine covers news, features, reviews and commentary on science, technology and their implications. ''New Scientist'' also publishes speculative articles, ranging from the technical to the philosophical. ''New Scientist'' was acquired by Daily Mail and General Trust (DMGT) in March 2021. History Ownership The magazine was founded in 1956 by Tom Margerison, Max Raison and Nicholas Harrison as ''The New Scientist'', with Issue 1 on 22 November 1956, priced at one shilling (). An article in the magazi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rotterdam
Rotterdam ( , ; ; ) is the second-largest List of cities in the Netherlands by province, city in the Netherlands after the national capital of Amsterdam. It is in the Provinces of the Netherlands, province of South Holland, part of the North Sea mouth of the Rhine–Meuse–Scheldt delta, via the Nieuwe Maas, New Meuse inland shipping channel, dug to connect to the Meuse at first and now to the Rhine. Rotterdam's history goes back to 1270, when a dam was constructed in the Rotte (river), Rotte. In 1340, Rotterdam was granted city rights by William II, Count of Hainaut, William IV, Count of Holland. The Rotterdam–The Hague metropolitan area, with a population of approximately 2.7 million, is the List of urban areas in the European Union, 10th-largest in the European Union and the most populous in the country. A major logistic and economic centre, Rotterdam is Port of Rotterdam, Europe's largest seaport. In 2022, Rotterdam had a population of 655,468 and is home to over 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Single-nucleotide Polymorphism
In genetics and bioinformatics, a single-nucleotide polymorphism (SNP ; plural SNPs ) is a germline substitution of a single nucleotide at a specific position in the genome. Although certain definitions require the substitution to be present in a sufficiently large fraction of the population (e.g. 1% or more), many publications do not apply such a frequency threshold. For example, a Guanine, G nucleotide present at a specific location in a reference genome may be replaced by an Adenine, A in a minority of individuals. The two possible nucleotide variations of this SNP – G or A – are called alleles. SNPs can help explain differences in susceptibility to a wide range of diseases across a population. For example, a common SNP in the Factor H, CFH gene is associated with increased risk of age-related macular degeneration. Differences in the severity of an illness or response to treatments may also be manifestations of genetic variations caused by SNPs. For example, two ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and non-coding genes. During gene expression (the synthesis of Gene product, RNA or protein from a gene), DNA is first transcription (biology), copied into RNA. RNA can be non-coding RNA, directly functional or be the intermediate protein biosynthesis, template for the synthesis of a protein. The transmission of genes to an organism's offspring, is the basis of the inheritance of phenotypic traits from one generation to the next. These genes make up different DNA sequences, together called a genotype, that is specific to every given individual, within the gene pool of the population (biology), population of a given species. The genotype, along with environmental and developmental factors, ultimately determines the phenotype ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
