Portal:Biology
Introduction
Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary information encoded in genes, which can be transmitted to future generations. Another major theme is evolution, which explains the unity and diversity of life. Energy processing is also important to life as it allows organisms to move, grow, and reproduce. Finally, all organisms are able to regulate their own internal environments.
Biologists are able to study life at multiple levels of organization, from the molecular biology of a cell to the anatomy and physiology of plants and animals, and evolution of populations. Hence, there are multiple subdisciplines within biology, each defined by the nature of their research questions and the tools that they use. Like other scientists, biologists use the scientific method to make observations, pose questions, generate hypotheses, perform experiments, and form conclusions about the world around them.
Life on Earth, which emerged more than 3.7 billion years ago, is immensely diverse. Biologists have sought to study and classify the various forms of life, from prokaryotic organisms such as archaea and bacteria to eukaryotic organisms such as protists, fungi, plants, and animals. These various organisms contribute to the biodiversity of an ecosystem, where they play specialized roles in the cycling of nutrients and energy through their biophysical environment. (Full article...)
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A prokaryote (/proʊˈkærioʊt, -ət/; less commonly spelled procaryote) is a single-cell organism whose cell lacks a nucleus and other membrane-bound organelles. The word prokaryote comes from the Ancient Greek πρό (pró), meaning 'before', and κάρυον (káruon), meaning 'nut' or 'kernel'. In the two-empire system arising from the work of Édouard Chatton, prokaryotes were classified within the empire Prokaryota. However in the three-domain system, based upon molecular analysis, prokaryotes are divided into two domains: Bacteria (formerly Eubacteria) and Archaea (formerly Archaebacteria). Organisms with nuclei are placed in a third domain: Eukaryota.
Prokaryotes evolved before eukaryotes, and lack nuclei, mitochondria, and most of the other distinct organelles that characterize the eukaryotic cell. It was once thought that prokaryotic cellular components were unenclosed within the cytoplasm except for an outer cell membrane, but bacterial microcompartments, which are thought to be quasi-organelles enclosed in protein shells (such as the encapsulin protein cages), have been discovered, along with other prokaryotic organelles. While being unicellular, some prokaryotes, such as cyanobacteria, may form colonies held together by biofilms, and large colonies can create multilayered microbial mats. Others, such as myxobacteria, have multicellular stages in their life cycles. Prokaryotes are asexual, reproducing via binary fission without any fusion of gametes, although horizontal gene transfer may take place. (Full article...)
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Chimaeras are cartilaginous fish in the order Chimaeriformes, known informally as ghost sharks, ratfish, spookfish, or rabbitfishes. They grow up to 150 cm (4.9 ft) in length, and have elongated, soft bodies, with a bulky head and a single gill-opening. For defense, most chimaeras have a venomous spine located in front of the dorsal fin. At one time a "diverse and abundant" group (based on the fossil record), their closest living relatives are sharks, though in evolutionary terms they branched off from sharks nearly 400 million years ago and have remained isolated ever since, typically confined to deep water.
Major topics
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Gregor Johann Mendel OSA (/ˈmɛndəl/; Czech: Řehoř Jan Mendel; 20 July 1822 – 6 January 1884) was an Austrian-Czech biologist, meteorologist, mathematician, Augustinian friar and abbot of St. Thomas' Abbey in Brno (Brünn), Margraviate of Moravia. Mendel was born in a German-speaking family in the Silesian part of the Austrian Empire (today's Czech Republic) and gained posthumous recognition as the founder of the modern science of genetics. Though farmers had known for millennia that crossbreeding of animals and plants could favor certain desirable traits, Mendel's pea plant experiments conducted between 1856 and 1863 established many of the rules of heredity, now referred to as the laws of Mendelian inheritance.
Mendel worked with seven characteristics of pea plants: plant height, pod shape and color, seed shape and color, and flower position and color. Taking seed color as an example, Mendel showed that when a true-breeding yellow pea and a true-breeding green pea were cross-bred, their offspring always produced yellow seeds. However, in the next generation, the green peas reappeared at a ratio of 1 green to 3 yellow. To explain this phenomenon, Mendel coined the terms "recessive" and "dominant" in reference to certain traits. In the preceding example, the green trait, which seems to have vanished in the first filial generation, is recessive, and the yellow is dominant. He published his work in 1866, demonstrating the actions of invisible "factors"—now called genes—in predictably determining the traits of an organism. (Full article...)
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Carefully engineered strains of the bacterium Escherichia coli are crucial tools in biotechnology as well as many other biological fields. (from History of biology) -
Charles Darwin's first sketch of an evolutionary tree from his First Notebook on Transmutation of Species (1837) (from History of biology) -
August Weismann's germ plasm theory. The hereditary material, the germ plasm, is confined to the gonads. Somatic cells (of the body) develop afresh in each generation from the germ plasm. (from History of genetics) -
Efforts are made to preserve the natural characteristics of Hopetoun Falls, Australia, without affecting visitors' access. (from Conservation biology) -
Clay models of animal livers dating between the nineteenth and eighteenth centuries BCE, found in the royal palace at Mari (from History of biology) -
Statue of Robert Koch in Berlin. Koch directly provided proof for the germ theory of diseases, therefore creating the scientific basis of public health, saving millions of lives. For his life's work Koch is seen as one of the founders of modern medicine. (from History of biology) -
Penicillin was viewed as a miracle drug that brought enormous profits and public expectations. (from History of biotechnology) -
Brewing was an early example of biotechnology (from History of biotechnology) -
Aristotle's model of transmission of movements from parents to child, and of form from the father. The model is not fully symmetric. (from History of genetics) -
Wendell Stanley's crystallization of tobacco mosaic virus as a pure nucleoprotein in 1935 convinced many scientists that heredity might be explained purely through physics and chemistry. (from History of biology) -
A Genentech-sponsored sign declaring South San Francisco to be "The Birthplace of Biotechnology." (from History of biotechnology) -
In Micrographia, Robert Hooke had applied the word cell to biological structures such as this piece of cork, but it was not until the 19th century that scientists considered cells the universal basis of life. (from History of biology) -
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A pie chart image showing the relative biomass representation in a rain forest through a summary of children's perceptions from drawings and artwork (left), through a scientific estimate of actual biomass (middle), and by a measure of biodiversity (right). The biomass of social insects (middle) far outweighs the number of species (right). (from Conservation biology) -
Frontispiece to a 1644 version of the expanded and illustrated edition of Historia Plantarum, originally written by Theophrastus around 300 BCE (from History of biology) -
Gregor Mendel, "father of modern genetics" (from History of biology) -
Cabinets of curiosities, such as that of Ole Worm, were centers of biological knowledge in the early modern period, bringing organisms from across the world together in one place. Before the Age of Exploration, naturalists had little idea of the sheer scale of biological diversity. (from History of biology) -
De arte venandi, by Frederick II, Holy Roman Emperor, was an influential medieval natural history text that explored bird morphology. (from History of biology) -
Some biodiversity loss is more insidious than others due to systemic neglect. For example, sport killing and wanton waste of tons of native fishes from unregulated 21st century bowfishing in the United States. New conservation movements are needed to deter irreparable biodiversity loss to fragile freshwater ecosystems. (from Conservation biology) -
A biomedical work by Ibn al-Nafis, an early adherent of experimental dissection who discovered the pulmonary and coronary circulation (from History of biology) -
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2016 conservation indicator which includes the following indicators: marine protected areas, terrestrial biome protection (global and national), and species protection (global and national) (from Conservation biology) -
The frontispiece to Erasmus Darwin's evolution-themed poem The Temple of Nature shows a goddess pulling back the veil from nature (in the person of Artemis). Allegory and metaphor have often played an important role in the history of biology. (from History of biology) -
The "central dogma of molecular biology" (originally a "dogma" only in jest) was proposed by Francis Crick in 1958. This is Crick's reconstruction of how he conceived of the central dogma at the time. The solid lines represent (as it seemed in 1958) known modes of information transfer, and the dashed lines represent postulated ones. (from History of biology) -
Description of rare animals (写生珍禽图), by Huang Quan (903–965) during the Song dynasty (from History of biology) -
Synthetic insulin crystals synthesized using recombinant DNA technology (from History of biotechnology) -
Thomas Hunt Morgan discovered sex linked inheritance of the white eyed mutation in the fruit fly Drosophila in 1910, implying the gene was on the sex chromosome. (from History of genetics) -
Innovative laboratory glassware and experimental methods developed by Louis Pasteur and other biologists contributed to the young field of bacteriology in the late 19th century. (from History of biology) -
Diagram of Charles Darwin's pangenesis theory. Every part of the body emits tiny particles, gemmules, which migrate to the gonads and contribute to the fertilised egg and so to the next generation. The theory implied that changes to the body during an organism's life would be inherited, as proposed in Lamarckism. (from History of genetics) -
Blending Inheritance (from History of genetics) -
Thomas Hunt Morgan's illustration of crossing over, part of the Mendelian-chromosome theory of heredity (from History of biology) -
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More conservation research is needed for understanding ecology and behaviour of the dhole in central China. (from Conservation biology) -
Mendelian inheritance states characteristics are discrete and are inherited by the parents. This image depicts a monohybrid cross and shows 3 generations: P1 generation (1), F1 generation (2), and F2 generation (3). Each organism inherits two alleles, one from each parent, that make up the genotype. The observed characteristic, the phenotype, is determined by the dominant allele in the genotype. In this monohybrid cross the dominant allele encodes for the colour red and the recessive allele encodes for the colour white. (from History of genetics) -
An art scape image showing the relative importance of animals in a rain forest through a summary of (a) child's perception compared with (b) a scientific estimate of the importance. The size of the animal represents its importance. The child's mental image places importance on big cats, birds, butterflies, and then reptiles versus the actual dominance of social insects (such as ants). (from Conservation biology) -
Summary of 2006 IUCN Red List categories: EX (Extinct) — EW (Extinct in the Wild) — CR (Critically Endangered) — EN (Endangered) — VU (Vulnerable) — NT (Near Threatened) — LC (Least Concern) (from Conservation biology) -
In the course of his travels, Alexander von Humboldt mapped the distribution of plants across landscapes and recorded a variety of physical conditions such as pressure and temperature. (from History of biology) -
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Inside of a 48-well thermal cycler, a device used to perform polymerase chain reaction on many samples at once (from History of biology)
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Did you know -
- ... that endemics along the wildlife of Morocco include more than six hundred species of vascular plants and a single species of bird?
- ... that an extract of Alchemilla diademata, a plant endemic to Lebanon, shows antimicrobial activity against Staphylococcus aureus?
- ... that more than 5,000 hen fleas were recorded from the nest of a coal tit?
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