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Phototactic
Phototaxis is a kind of taxis, or locomotory movement, that occurs when a whole organism moves towards or away from a stimulus (physiology), stimulus of light. This is advantageous for phototrophic organisms as they can orient themselves most efficiently to receive light for photosynthesis. Phototaxis is called positive if the movement is in the direction of increasing light intensity and negative if the direction is opposite. Phototaxis has been described in microorganisms and algea, insects and other invertebrates, and vertebrates. Typically nocturnal insects can show positive phototaxis, while nocturnal mammals often show negative phototaxis. Phototaxis in bacteria and archea Phototaxis can be advantageous for phototrophic bacteria as they can orient themselves most efficiently to receive light for photosynthesis. Phototaxis is called positive if the movement is in the direction of increasing light intensity and negative if the direction is opposite. Two types of positive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photoreceptor Protein
Photoreceptor proteins are light-sensitive proteins involved in the sensing and response to light in a variety of organisms. Some examples are rhodopsin in the photoreceptor cells of the vertebrate retina, phytochrome in plants, and bacteriorhodopsin and bacteriophytochromes in some bacteria. They mediate light responses as varied as visual perception, phototropism and phototaxis, as well as responses to light-dark cycles such as circadian rhythm and other photoperiodisms including control of flowering times in plants and mating seasons in animals. Structure Photoreceptor proteins typically consist of a protein attached to a non-protein chromophore (sometimes referred as photopigment, even so photopigment may also refer to the photoreceptor as a whole). The chromophore reacts to light via photoisomerization or photoreduction, thus initiating a change of the receptor protein which triggers a signal transduction cascade. Chromophores found in photoreceptors include retinal ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taxis
A taxis (; : taxes ) is the motility, movement of an organism in response to a Stimulus (physiology), stimulus such as light or the presence of food. Taxes are innate behavioural responses. A taxis differs from a tropism (turning response, often growth towards or away from a stimulus) in that in the case of taxis, the organism has motility and demonstrates guided movement towards or away from the stimulus source. It is sometimes distinguished from a Kinesis (biology), kinesis, a non-directional change in activity in response to a stimulus. Taxis can be positive (moving towards the stimulus) or negative (moving away from the stimulus). Classification Taxes are classified based on the type of stimulus, and on whether the organism's response is to move towards or away from the stimulus. If the organism moves towards the stimulus the taxis are positive, while if it moves away the taxis are negative. For example, flagellate protozoans of the genus ''Euglena'' move towards a light so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distribution Of Three-dimensional Phototaxis In The Tree Of Eukaryotes
Distribution may refer to: Mathematics *Distribution (mathematics), generalized functions used to formulate solutions of partial differential equations *Probability distribution, the probability of a particular value or value range of a variable **Cumulative distribution function, in which the probability of being no greater than a particular value is a function of that value *Frequency distribution, a list of the values recorded in a sample * Inner distribution, and outer distribution, in coding theory *Distribution (differential geometry), a subset of the tangent bundle of a manifold * Distributed parameter system, systems that have an infinite-dimensional state-space *Distribution of terms, a situation in which all members of a category are accounted for *Distributivity, a property of binary operations that generalises the distributive law from elementary algebra *Distribution (number theory) *Distribution problems, a common type of problems in combinatorics where the goal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Filamentous Cyanobacterium
Cyanobacterial morphology refers to the form or shape of cyanobacteria. Cyanobacteria are a large and diverse phylum of bacteria defined by their unique combination of pigments and their ability to perform oxygenic photosynthesis. Cyanobacteria often live in colonial aggregates that can take a multitude of forms. Of particular interest among the many species of cyanobacteria are those that live colonially in elongate hair-like structures, known as trichomes. These filamentous species can contain hundreds to thousands of cells. They often dominate the upper layers of microbial mats found in extreme environments such as hot springs, hypersaline water, deserts and polar regions, as well as being widely distributed in more mundane environments. Many filamentous species are also motile, gliding along their long axis, and displaying photomovement by which a trichome modulates its gliding according to the incident light. The latter has been found to play an important role in guiding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synechocystis
''Synechocystis'' is a genus of unicellular, freshwater cyanobacteria in the family Merismopediaceae. It includes a strain, ''Synechocystis'' sp. PCC 6803, which is a well studied model organism A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workings of other organisms. Mo .... Like all cyanobacteria, ''Synechocystis'' branches on the evolutionary tree from its ancestral root, '' Gloeobacter violaceus''. ''Synechocystis'' is not diazotrophic, and is closely related to another model organism, '' Cyanothece'' ATCC 51442. It has been suggested that originally ''Synechocystis'' possessed the ability to fix atmospheric nitrogen, but lost the genes required for the process. ''Synechocystis'' can detect light and move in the direction of light. See also * ''Synechocystis'' run-and-tumble References {{Taxon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anabaena
''Anabaena'' is a genus of filamentous cyanobacteria that exist as plankton. They are known for nitrogen-fixing abilities, and they form symbiotic relationships with certain plants, such as the mosquito fern. They are one of four genera of cyanobacteria that produce neurotoxins, which are harmful to local wildlife, as well as farm animals and pets. Production of these neurotoxins is assumed to be an input into its symbiotic relationships, protecting the plant from grazing pressure. A DNA sequencing project was undertaken by the United States Department of Energy between 1999 and 2005. This project mapped the complete genome of model organism ''Anabaena variabilis'' ATCC 29413, which is 7.2 million base pairs long. A paper detailing the process was published in 2014. The study focused on heterocysts, which convert nitrogen into ammonia. Certain species of ''Anabaena'' have been used on rice paddy fields, proving to be an effective natural fertilizer. Species List of current ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CC-BY Icon
A Creative Commons (CC) license is one of several public copyright licenses that enable the free distribution of an otherwise copyrighted "work". A CC license is used when an author wants to give other people the right to share, use, and build upon a work that the author has created. CC provides an author flexibility (for example, they might choose to allow only non-commercial uses of a given work) and protects the people who use or redistribute an author's work from concerns of copyright infringement as long as they abide by the conditions that are specified in the license by which the author distributes the work. There are several types of Creative Commons licenses. Each license differs by several combinations that condition the terms of distribution. They were initially released on December 16, 2002, by Creative Commons, a U.S. non-profit corporation founded in 2001. There have also been five versions of the suite of licenses, numbered 1.0 through 4.0. Released in November ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Histidine Kinase
Histidine kinases (HK) are multifunctional, and in non-animal kingdoms, typically transmembrane, proteins of the transferase class of enzymes that play a role in signal transduction across the cellular membrane. The vast majority of HKs are homodimers that exhibit autokinase, phosphotransfer, and phosphatase activity. HKs can act as cellular receptors for signaling molecules in a way analogous to tyrosine kinase receptors (RTK). Multifunctional receptor molecules such as HKs and RTKs typically have portions on the outside of the cell (extracellular domain) that bind to hormone- or growth factor-like molecules, portions that span the cell membrane ( transmembrane domain), and portions within the cell (intracellular domain) that contain the enzymatic activity. In addition to kinase activity, the intracellular domains typically have regions that bind to a secondary effector molecule or complex of molecules that further propagate signal transduction within the cell. Distinct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SRI (gene)
Sorcin is a protein that in humans is encoded by the ''SRI'' 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: protei .... Interactions SRI (gene) has been shown to interact with Ryanodine receptor 2, ANXA7 and GCA. References Further reading * * * * * * * * * * * * * * * * * {{gene-7-stub Penta-EF-hand proteins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isomerization
In chemistry, isomerization or isomerisation is the process in which a molecule, polyatomic ion or molecular fragment is transformed into an isomer with a different chemical structure. Enolization is an example of isomerization, as is tautomerization. When the activation energy for the isomerization reaction is sufficiently small, both isomers can often be observed and the equilibrium ratio will shift in a temperature-dependent equilibrium with each other. Many values of the standard free energy difference, \Delta G^\circ, have been calculated, with good agreement between observed and calculated data. Examples and applications Alkanes Skeletal isomerization occurs in the cracking process, used in the petrochemical industry to convert straight chain alkanes to isoparaffins as exemplified in the conversion of normal octane to 2,5-dimethylhexane (an "isoparaffin"): : Fuels containing branched hydrocarbons are favored for internal combustion engines for their higher octan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromophore
A chromophore is the part of a molecule responsible for its color. The word is derived . The color that is seen by our eyes is that of the light not Absorption (electromagnetic radiation), absorbed by the reflecting object within a certain wavelength spectrum of visible spectrum, visible light. The chromophore is a region in the molecule where the energy difference between two separate molecular orbitals falls within the range of the visible spectrum (or in informal contexts, the spectrum under scrutiny). Visible light that hits the chromophore can thus be absorbed by exciting an electron from its ground state into an excited state. In biological molecules that serve to capture or detect light energy, the chromophore is the Moiety (chemistry), moiety that causes a conformational change in the molecule when hit by light. Conjugated pi-bond system chromophores Just like how two adjacent p-orbitals in a molecule will form a pi-bond, three or more adjacent p-orbitals in a molec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retinal
Retinal (also known as retinaldehyde) is a polyene chromophore. Retinal, bound to proteins called opsins, is the chemical basis of visual phototransduction, the light-detection stage of visual perception (vision). Some microorganisms use retinal to convert light into metabolic energy. One study suggests that approximately three billion years ago, most living organisms on Earth used retinal, rather than chlorophyll, to convert sunlight into energy. Because retinal absorbs mostly green light and transmits purple light, this gave rise to the Purple Earth hypothesis. Retinal itself is considered to be a form of vitamin A when eaten by an animal. There are many forms of vitamin A, all of which are converted to retinal, which cannot be made without them. The number of different molecules that can be converted to retinal varies from species to species. Retinal was originally called retinene, and was renamed after it was discovered to be vitamin A aldehyde. Vertebrate animals inge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
