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/) is a single-celled organism that lacks a nucleus, and other membrane-bound organelles. The word prokaryote comes from the Greek πρό (pro, 'before') and κάρυον (karyon, 'nut' or 'kernel'). In the two-empire system arising from the work of Édouard Chatton, prokaryotes were classified within the empire Prokaryota. But 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. In the study of the origins of life, prokaryotes are thought to have arisen before eukaryotes.
Besides the absence of a nucleus, prokaryotes also lack mitochondria, or most of the other membrane-bound organelles that characterize the eukaryotic cell. It was once thought that prokaryotic cellular components within the cytoplasm were unenclosed, except for an outer cell membrane, but bacterial microcompartments, which are thought to be simple organelles enclosed in protein shells, have been discovered, along with other prokaryotic organelles. While being unicellular, some prokaryotes, such as cyanobacteria, may form large colonies. Others, such as myxobacteria, have multicellular stages in their life cycles. Prokaryotes are asexual, reproducing without fusion of gametes, although horizontal gene transfer also takes place. (Full article...)Selected picture -
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A biomedical work by Ibn al-Nafis, an early adherent of experimental dissection who discovered the pulmonary and coronary circulation (from History of biology)
Display of VNTR allele lengths on a chromatogram, a technology used in DNA fingerprinting (from History of genetics)
Description of rare animals (写生珍禽图), by Huang Quan (903–965) during the Song dynasty. (from History of biology)
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)
Efforts are made to preserve the natural characteristics of Hopetoun Falls, Australia, without affecting visitors' access. (from Conservation biology)
A Genentech-sponsored sign declaring South San Francisco to be "The Birthplace of Biotechnology." (from History of biotechnology)
In 1972, the first gene was sequenced: the gene for bacteriophage MS2 coat protein (3 chains in different colours). (from History of genetics)
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)
Blending Inheritance (from History of genetics)
Carefully engineered strains of the bacterium Escherichia coli are crucial tools in biotechnology as well as many other biological fields. (from History of biology)
Meselson–Stahl experiment demonstrates DNA is semiconservatively replicated. (from History of genetics)
Clay models of animal livers dating between the nineteenth and eighteenth centuries BCE, found in the royal palace at Mari (from History of 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 color red and the recessive allele encodes for the color white. (from History of genetics)
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)
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)
Charles Darwin's first sketch of an evolutionary tree from his First Notebook on Transmutation of Species (1837) (from History of biology)
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)
Roosevelt and Muir on Glacier Point in Yosemite National Park (from Conservation 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)
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)
Inside of a 48-well thermal cycler, a device used to perform polymerase chain reaction on many samples at once (from History of biology)
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)
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)
Thomas Hunt Morgan's illustration of crossing over, part of the Mendelian-chromosome theory of heredity (from History of biology)
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). Notice that the biomass of social insects (middle) far outweighs the number of species (right). (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)
Synthetic insulin crystals synthesized using recombinant DNA technology (from History of biotechnology)
Brewing was an early example of biotechnology (from History of biotechnology)
Sperms as preformed humans. Painting of Nicolaas Hartsoeker 1695 (from History of genetics)
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)
Hershey–Chase experiment proves that phage genetic material is DNA. (from History of genetics)
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)
De arte venandi, by Frederick II, Holy Roman Emperor, was an influential medieval natural history text that explored bird morphology. (from History of biology)
In Griffith's experiment, mice are injected with dead bacteria of one strain and live bacteria of another, and develop an infection of the dead strain's type. (from History of genetics)
Frontispiece to a 1644 version of the expanded and illustrated edition of Historia Plantarum, originally written by Theophrastus around 300 BC (from History of biology)
White gyrfalcons drawn by John James Audubon (from Conservation biology)
More conservation research is needed for understanding ecology and behaviour of asiatic wild dog in central China. (from Conservation biology)
Tadrart Acacus desert in western Libya, part of the Sahara (from Conservation biology)
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)
Francis Collins announces the successful completion of the Human Genome Project in 2003 (from History of genetics)
Penicillin was viewed as a miracle drug that brought enormous profits and public expectations. (from History of biotechnology)
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Did you know -
- ... that seeds of the fossil fruit Suciacarpa have fossil fungi inside them?
- ... that the fossil ant genus Agastomyrma was described from a single queen, and males of the fossil ant Proceratium eocenicum have a hair fringe?
- ... that less than 50 years after being discovered, Heterelmis stephani is now presumed extinct?
- ... that in 1981 Bobbi Campbell became the first person to publicly identify as a person living with HIV/AIDS?
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