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Phototropic
Phototropism is the growth of an organism in response to a light stimulus. Phototropism is most often observed in plants, but can also occur in other organisms such as fungi. The cells on the plant that are farthest from the light contain a hormone called auxin that reacts when phototropism occurs. This causes the plant to have elongated cells on the furthest side from the light. Phototropism is one of the many plant tropisms or movements which respond to external stimuli. Growth towards a light source is called positive phototropism, while growth away from light is called negative phototropism. Negative phototropism is not to be confused with skototropism which is defined as the growth towards darkness, whereas negative phototropism can refer to either the growth away from a light source or towards the darkness. Most plant shoots exhibit positive phototropism, and rearrange their chloroplasts in the leaves to maximize photosynthetic energy and promote growth.Goyal, A., Szarzyn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Auxin Action
Auxins (plural of auxin ) are a class of plant hormones (or plant-growth regulators) with some morphogen-like characteristics. Auxins play a cardinal role in coordination of many growth and behavioral processes in plant life cycles and are essential for plant body development. The Dutch biologist Frits Warmolt Went first described auxins and their role in plant growth in the 1920s. Kenneth V. Thimann became the first to isolate one of these phytohormones and to determine its chemical structure as indole-3-acetic acid (IAA). Went and Thimann co-authored a book on plant hormones, ''Phytohormones'', in 1937. Overview Auxins were the first of the major plant hormones to be discovered. They derive their name from the Greek word αυξειν (''auxein'' – "to grow/increase"). Auxin is present in all parts of a plant, although in very different concentrations. The concentration in each position is crucial developmental information, so it is subject to tight regulation through both metab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Auxin
Auxins (plural of auxin ) are a class of plant hormones (or plant-growth regulators) with some morphogen-like characteristics. Auxins play a cardinal role in coordination of many growth and behavioral processes in plant life cycles and are essential for plant body development. The Dutch biologist Frits Warmolt Went first described auxins and their role in plant growth in the 1920s. Kenneth V. Thimann became the first to isolate one of these phytohormones and to determine its chemical structure as indole-3-acetic acid (IAA). Went and Thimann co-authored a book on plant hormones, ''Phytohormones'', in 1937. Overview Auxins were the first of the major plant hormones to be discovered. They derive their name from the Greek word αυξειν (''auxein'' – "to grow/increase"). Auxin is present in all parts of a plant, although in very different concentrations. The concentration in each position is crucial developmental information, so it is subject to tight regulation through both ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phytochrome
Phytochromes are a class of photoreceptor in plants, bacteria and fungi used to detect light. They are sensitive to light in the red and far-red region of the visible spectrum and can be classed as either Type I, which are activated by far-red light, or Type II that are activated by red light. Recent advances have suggested that phytochromes also act as temperature sensors, as warmer temperatures enhance their de-activation. All of these factors contribute to the plant's ability to germinate. Phytochromes control many aspects of plant development. They regulate the germination of seeds (photoblasty), the synthesis of chlorophyll, the elongation of seedlings, the size, shape and number and movement of leaves and the timing of flowering in adult plants. Phytochromes are widely expressed across many tissues and developmental stages. Other plant photoreceptors include cryptochromes and phototropins, which respond to blue and ultraviolet-A light and UVR8, which is sensitive to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arabidopsis Thaliana
''Arabidopsis thaliana'', the thale cress, mouse-ear cress or arabidopsis, is a small flowering plant native to Eurasia and Africa. ''A. thaliana'' is considered a weed; it is found along the shoulders of roads and in disturbed land. A winter annual with a relatively short lifecycle, ''A. thaliana'' is a popular model organism in plant biology and genetics. For a complex multicellular eukaryote, ''A. thaliana'' has a relatively small genome around 135 megabase pairs. It was the first plant to have its genome sequenced, and is a popular tool for understanding the molecular biology of many plant traits, including flower development and light sensing. Description ''Arabidopsis thaliana'' is an annual (rarely biennial) plant, usually growing to 20–25 cm tall. The leaves form a rosette at the base of the plant, with a few leaves also on the flowering stem. The basal leaves are green to slightly purplish in color, 1.5–5 cm long, and 2–10 mm broad, wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cholodny–Went Model
In botany, the Cholodny–Went model, proposed in 1927, is an early model describing tropism in emerging shoots of monocotyledons, including the tendencies for the shoot to grow towards the light (phototropism) and the roots to grow downward (gravitropism Gravitropism (also known as geotropism) is a coordinated process of differential growth by a plant in response to gravity pulling on it. It also occurs in fungi. Gravity can be either "artificial gravity" or natural gravity. It is a general feat ...). In both cases the directional growth is considered to be due to asymmetrical distribution of auxin, a plant growth hormone. Although the model has been criticized and continues to be refined, it has largely stood the test of time. Basic model The model was independently proposed by the Russian scientist Nikolai Cholodny of the University of Kyiv in 1927 and by Frits Warmolt Went of the California Institute of Technology in 1928, both based on work they had done in 1926. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phototropin
Phototropins are photoreceptor proteins (more specifically, flavoproteins) that mediate phototropism responses in higher plants. Phototropins can be found throughout the leaves of a plant. Along with cryptochromes and phytochromes they allow plants to respond and alter their growth in response to the light environment. Phototropins may also be important for the opening of stomata and the movement of chloroplasts. These blue light receptors are seen across the entire green plant lineage. When Phototropins are hit with blue light, they induce a signal transduction pathway that alters the plant cells' functions in different ways. Phototropins are part of the phototropic sensory system in plants that causes various environmental responses in plants. Phototropins specifically will cause stems to bend towards light and stomata to open. Phototropins have been shown to impact the movement of chloroplast inside the cell. In addition phototropins mediate the first changes in stem elongati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coleoptile
Coleoptile is the pointed protective sheath covering the emerging shoot in monocotyledons such as grasses in which few leaf primordia and shoot apex of monocot embryo remain enclosed. The coleoptile protects the first leaf as well as the growing stem in seedlings and eventually, allows the first leaf to emerge. Coleoptiles have two vascular bundles, one on either side. Unlike the flag leaves rolled up within, the pre-emergent coleoptile does not accumulate significant protochlorophyll or carotenoids, and so it is generally very pale. Some preemergent coleoptiles do, however, accumulate purple anthocyanin pigments. Coleoptiles consist of very similar cells that are all specialised to fast stretch growth. They do not divide, but increase in size as they accumulate more water. Coleoptiles also have water vessels (frequently two) along the axis to provide a water supply. When a coleoptile reaches the surface, it stops growing and the flag leaves penetrate its top, continuing to grow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Science (journal)
''Science'', also widely referred to as ''Science Magazine'', is the peer-reviewed academic journal of the American Association for the Advancement of Science (AAAS) and one of the world's top academic journals. It was first published in 1880, is currently circulated weekly and has a subscriber base of around 130,000. Because institutional subscriptions and online access serve a larger audience, its estimated readership is over 400,000 people. ''Science'' is based in Washington, D.C., United States, with a second office in Cambridge, UK. Contents The major focus of the journal is publishing important original scientific research and research reviews, but ''Science'' also publishes science-related news, opinions on science policy and other matters of interest to scientists and others who are concerned with the wide implications of science and technology. Unlike most scientific journals, which focus on a specific field, ''Science'' and its rival ''Nature'' cover the full ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biology Terminology
This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms. It is intended as introductory material for novices; for more specific and technical definitions from sub-disciplines and related fields, see Glossary of genetics, Glossary of evolutionary biology, Glossary of ecology, and Glossary of scientific naming, or any of the organism-specific glossaries in :Glossaries of biology. A B C D E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scotobiology
Scotobiology is the study of biology as directly and specifically affected by darkness, as opposed to photobiology, which describes the biological effects of light. Overview The science of scotobiology gathers together under a single descriptive heading a wide range of approaches to the study of the biology of darkness. This includes work on the effects of darkness on the behavior and metabolism of animals, plants, and microbes. Some of this work has been going on for over a century, and lays the foundation for understanding the importance of dark night skies, not only for humans but for all biological species. The great majority of biological systems have evolved in a world of alternating day and night and have become irrevocably adapted to and dependent on the daily and seasonally changing patterns of light and darkness. Light is essential for many biological activities such as sight and photosynthesis. These are the focus of the science of photobiology. But the prese ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Democratic Republic Of Congo
The Democratic Republic of the Congo (french: République démocratique du Congo (RDC), colloquially "La RDC" ), informally Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly and also colloquially Zaire, is a country in Central Africa. It is bordered to the northwest by the Republic of the Congo, to the north by the Central African Republic, to the northeast by South Sudan, to the east by Uganda, Rwanda, and Burundi, and by Tanzania (across Lake Tanganyika), to the south and southeast by Zambia, to the southwest by Angola, and to the west by the South Atlantic Ocean and the Cabinda exclave of Angola. By area, it is the second-largest country in Africa and the 11th-largest in the world. With a population of around 108 million, the Democratic Republic of the Congo is the most populous officially Francophone country in the world. The national capital and largest city is Kinshasa, which is also the nation's economic center. Centered on the Congo Ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
