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Basal Definition Biology

Basal Core Promoters Control The Equilibrium Between Negative Cofactor 2 And Preinitiation Complexes In Human Cells

Basal Core Promoters Control The Equilibrium Between Negative Cofactor 2 And Preinitiation Complexes In Human Cells

Basal core promoters control the equilibrium between negative cofactor 2 and preinitiation complexes in human cells Albert et al.; licensee BioMed Central Ltd.2010 The general transcription factor TFIIB and its antagonist negative cofactor 2 (NC2) are hallmarks of RNA polymerase II (RNAPII) transcription. Both factors bind TATA box-binding protein (TBP) at promoters in a mutually exclusive manner. Dissociation of NC2 is thought to be followed by TFIIB association and subsequent preinitiation complex formation. TFIIB dissociates upon RNAPII promoter clearance, thereby providing a specific measure for steady-state preinitiation complex levels. As yet, genome-scale promoter mapping of human TFIIB has not been reported. It thus remains elusive how human core promoters contribute to preinitiation complex formation in vivo. We compare target genes of TFIIB and NC2 in human B cells and analyze associated core promoter architectures. TFIIB occupancy is positively correlated with gene expression, with the vast majority of promoters being GC-rich and lacking defined core promoter elements. TATA elements, but not the previously in vitro defined TFIIB recognition elements, are enriched in some 4 to 5% of the genes. NC2 binds to a highly related target gene set. Nonetheless, subpopulations show strong variations in factor ratios: whereas high TFIIB/NC2 ratios select for promoters with focused start sites and conserved core elements, high NC2/TFIIB ratios correlate to multiple start-site promoters lacking defined core elements. TFIIB and NC2 are global players that occupy active genes. Preinitiation complex formation is independent of core elements at the majority of genes. TATA and TATA-like elements dictate TFIIB occupancy at a subset of genes. Biochemical data support a model in Continue reading >>

Basal - Definition Of Basal By The Free Dictionary

Basal - Definition Of Basal By The Free Dictionary

Basal - definition of basal by The Free Dictionary a. Of, relating to, located at, or forming a base. b. Botany Located at or near the base of a plant stem, or at the base of any other plant part: basal placentation. 2. of or constituting a foundation or basis; fundamental; essential 2. forming a basis; fundamental; basic: a basal reader. a. indicating a standard low level of activity of an organism, as during total rest. b. of an amount required to maintain this level. basal - especially of leaves; located at the base of a plant or stem; especially arising directly from the root or rootstock or a root-like stem; "basal placentation"; "radical leaves" phytology , botany - the branch of biology that studies plants basal - serving as or forming a base; "the painter applied a base coat followed by two finishing coats" basic - pertaining to or constituting a base or basis; "a basic fact"; "the basic ingredients"; "basic changes in public opinion occur because of changes in priorities" essential - basic and fundamental; "the essential feature" the basal layer of the skin la couche basale de l'piderme ___ ganglia diseases enfermedades de los ganglios ___ -es; ___ metabolic rate ndice del metabolismo ___. Want to thank TFD for its existence? Tell a friend about us , add a link to this page, or visit the webmaster's page for free fun content . At the other end of the series we have the cells of the hive-bee, placed in a double layer: each cell, as is well known, is an hexagonal prism, with the basal edges of its six sides bevelled so as to join on to a pyramid, formed of three rhombs. Even in the rude circumferential rim or wall of wax round a growing comb, flexures may sometimes be observed, corresponding in position to the planes of the rhombic basal plates of future cells. Continue reading >>

What Is Apical And What Is Basal In Plant Root Development?

What Is Apical And What Is Basal In Plant Root Development?

What is apical and what is basal in plant root development? Baluka, Frantiek and Barlow, Peter W. and Baskin, Tobias I. and Chen, Rujin J. and Feldman, Lewis and Forde, Brian G. and Geisler, Markus and Jernstedt, Judy and Menzel, Diedrik and Muday, Gloria K. and Murphy, Angus and amaj, Jozef and Volkmann, Dieter (2005) What is apical and what is basal in plant root development? Trends in Plant Science, 10 (9). pp. 409-411. ISSN 1360-1385 Full text not available from this repository. Plant architecture is complex but well described by an established terminology that includes clear definitions of organismal polarity [1]. However, the definitions of polarity that apply to most stages of plant development cannot be applied to early zygotic development. Recent introduction of terminology reserved for early embryonic anatomy to post embryonic seedling anatomy have created some confusion. In this letter, we highlight the issue with the intention of clarifying terminology and bringing about a consensus regarding usage. The original Latin word apex refers to the summit of a hill, mountain or building. According to both the Oxford and Webster dictionaries, apex is defined as the highest or topmost point of a structure. In plants, an apex constitutes the tip of a shoot or a root. The word apical, therefore, means relating to, located or situated at, or constituting, an apex. A base is defined as the lowest or bottom part of an object on which it stands or the main part to which other parts are added. In biology, base means the part of a plant or animal organ that is near the point of attachment to the ground or to a more basal part of the body. Because we cannot say that plants stand on their roots, the base of both stems and roots is actually the same point, and is where the two Continue reading >>

Nodes, Branches, And Phylogenetic Definitions

Nodes, Branches, And Phylogenetic Definitions

Nodes, Branches, and Phylogenetic Definitions Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA *Correspondence to be sent to: Division of Amphibians & Reptiles, National Museum of Natural History, Smithsonian Institution, P.O. Box 37012, NHB, WG-7, MRC 162, Washington, DC 20013-7012, USA; E-mail: [email protected] Search for other works by this author on: Systematic Biology, Volume 62, Issue 4, 1 July 2013, Pages 625632, Kevin de Queiroz; Nodes, Branches, and Phylogenetic Definitions, Systematic Biology, Volume 62, Issue 4, 1 July 2013, Pages 625632, Adopting the perspective of graph theory, Martin et al. (2010) described two kinds of phylogenetic trees, which they termed node-based and stem- or branch-based, that differ with respect to the biological interpretations of their component nodes and branches. After establishing equivalency between the two different kinds of trees in terms of encoded information regarding taxa and their phylogenetic relationships, Martin et al. (2010) argued that node-based names should be applied only in the context of node-based trees, and that branch-based names should be applied only in the context of branch-based trees, because node-based names cannot exist on branch-based trees and vice versa. They also suggested that the International Code of Phylogenetic Nomenclature or PhyloCode ( Cantino and de Queiroz 2010 ) confuses the two kinds of names and trees and should therefore be amended to adopt one or the other of the two kinds of trees and the corresponding kind of names. In this contribution, I accept the distinction between the two kinds of phylogenetic trees described by Martin et al. (2010) , as well as their equivalency with regard to contained phylogenetic Continue reading >>

Basal Body - Dictionary Definition Of Basal Body | Encyclopedia.com: Free Online Dictionary

Basal Body - Dictionary Definition Of Basal Body | Encyclopedia.com: Free Online Dictionary

A Dictionary of Biology 2004, originally published by Oxford University Press 2004. basal body (kinetosome) See undulipodium . Pick a style below, and copy the text for your bibliography. " basal body. "A Dictionary of Biology..Encyclopedia.com.25 Apr. 2018< >. "basal body." A Dictionary of Biology.. Encyclopedia.com.(April 25, 2018). "basal body." A Dictionary of Biology.. RetrievedApril 25, 2018from Encyclopedia.com: Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA). Within the Cite this article tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list. Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, its best to use Encyclopedia.com citations as a starting point before checking the style against your school or publications requirements and the most-recent information available at these sites: Continue reading >>

Basal Body - An Overview | Sciencedirect Topics

Basal Body - An Overview | Sciencedirect Topics

The basal body is a continuation of the flagellum and is closely associated with the kinetoplast as they are connected via protein filaments. Susan K. Dutcher, in The Chlamydomonas Sourcebook , 2009 Duplication of basal bodies and centrioles generally occurs near existing basal bodies; this result suggests that the existing basal bodies may have a copy number control function. Chlamydomonas cells mutant for the gene VFL2 (centrin) show a randomization of basal body segregation, often producing daughter cells that lack intact basal bodies. Such cells lacking basal bodies are able to assemble new basal bodies de novo (Marshall et al., 2001). If there are no probasal bodies, then these results suggest that basal bodies can duplicate without a template. This de novo mechanism of basal body formation in Chlamydomonas is also observed in mammalian cells. The de novo mechanism may require more time than the templated mechanism. This lag may suggest that the initial events take more time to complete or that the presence of a basal body represses the formation of multiple basal bodies. Moreover, the number of new basal bodies made by the de novo pathway is random, which shows a loss of number control when preexisting basal bodies are not present. Control of basal body number is important for normal spindle assembly and integrity. Thomas H. Giddings, ... Mark Winey, in Methods in Cell Biology , 2010 Basal bodies and centrioles are highly ordered, microtubule-based organelles involved in the organization of the mitotic spindle and the formation of cilia and flagella. The ciliate Tetrahymena thermophila has more than 700 basal bodies per cell, making it an excellent choice for the study of the structure, function, and assembly of basal bodies. Here, we describe methods for cryofix Continue reading >>

Basal Ganglia Made Simple

Basal Ganglia Made Simple

The basal ganglia form a set of interconnected nuclei in the forebrain.Overall the basal ganglia receive a large amount of input from cerebralcortex, and after processing, send it back to cerebral cortex via thalamus.This major pathway led to the creation of the popular concept of cortico-basalganglia-cortical loops. Inside the basal ganglia there are too manyconnections and pathways to cover in this paragraph. Just briefly:The cortex sends excitatory input to the striatum. The principleneuron of the striatum is the famous medium spiny neuron, which sends itsinhibitory output on to the globus pallidus. The globus palliduscan also be excited by cortical activity, namely by a pathway that travelsthrough the subthalamic nucleus first. The globus pallidus is reallydivided into two segments, only one of which sends output (yet again inhibitory!)to the thalamus and on to cortex, thus completing the loop. The largersegment of globus pallidus (GPe) just inhibits the subthalamic nucleusand itself. The functional significance of this connection is stillquite mysterious! Similar to the cerebellum the basal ganglia arealso implicated in learning, and the system that is thought to be importanthere is the dopaminergic input received from the Substantia nigra parscompacta. Probably the best known fact regarding the basal gangliais that a lesion of this dopaminergic pathway causes Parkinsons disease. Numerous research projects have recorded electrical activity in thebasal ganglia. Unfortunately for the experimentalists seeking clearanswers, the recorded activity in behaving animals can be related justabout to any component of sensory input, motor preparation, and movementexecution. One thing is sure however: The medium spiny neuronsare active only at a very slow rate, and furthermore Continue reading >>

Basal

Basal

Also found in: Dictionary, Thesaurus, Legal, Acronyms, Encyclopedia, Wikipedia. Related to basal: Basal temperature, basal metabolic rate basal [ba´sal] pertaining to or situated near a base; in physiology, pertaining to the lowest possible level. Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved. ba·sal (bā'săl), [TA] 1. Situated nearer the base of a pyramidal organ in relation to a specific reference point; opposite of apical. Synonym(s): basalis [TA] 2. In dentistry, denoting the floor of a cavity in the grinding surface of a tooth. 3. Denoting a standard or reference state of a function, as a basis for comparison. More specifically, denoting the exact conditions for measurement of basal metabolic rate (q.v.); basal conditions do not always denote a minimum value, for example, metabolic rate in sleep is usually lower than the basal rate but is inconvenient for standard measurement. basal /ba·sal/ (ba´s'l) pertaining to or situated near a base; in physiology, pertaining to the lowest possible level. basal pertaining to the fundamental or the basic, as basal anesthesia, which produces the first stage of unconsciousness, and the basal metabolic rate, which indicates the lowest metabolic rate; basal membrane. basal adjective Referring to a base, baseline or non plus minimum. ba·sal (bā'săl) [TA] 1. Situated nearer the base of a pyramidal organ in relation to a specific reference point; opposite of apical. 2. dentistry Denoting the floor of a cavity in the grinding surface of a tooth. 3. Denoting a standard or reference state of a function, as a basis for comparison. basal Pertaining to, situated at, or forming, an anatomical base of any kind. ba Continue reading >>

Basal Bodies Platforms For Building Cilia.

Basal Bodies Platforms For Building Cilia.

1. Curr Top Dev Biol. 2008;85:1-22. doi: 10.1016/S0070-2153(08)00801-6. Basal bodies platforms for building cilia. (1)Department of Biochemistry and Biophysics, University of California, San Francisco, California, USA. Basal bodies are modified centrioles that give rise to cilia and flagella. Thebasal body is a complex structure that can form through at least two distinctpathways depending on the cell type. Corresponding to this structural complexity,the basal body proteome contains a large number of proteins, many of whichcorrespond to cilia-related disease genes, especially genes involved innephronophthisis and cone-rod dystrophy. Basal bodies appear to play severalroles in the cell. First, they provide a ninefold symmetric template on which theninefold symmetry axonemal structure of the cilium can be built. Second, theydictate the position and orientation of the cilium, which is especially critical for ensuring that cilia-driven fluid flows move in the correct direction. Third, they are the point at which entry of proteins into the cilium is regulated.Finally, recent evidence suggests that basal body position may be involved incoupling planar cell polarity cues with the axis of cell division. Defects in anyof these functions could lead to disease symptoms. Current studies of basal body biology include both proteomic and genetic approaches, relying on ciliated cellculture lines as well as genetically tractable systems such as Chlamydomonasreinhardtii. The "parts list" of basal body proteins and genes is rapidly beingcompleted, opening the way to more mechanistic studies in the future. Continue reading >>

Basal Angiosperms | Basic Biology

Basal Angiosperms | Basic Biology

The basal angiosperms are a broad group of the most primitive flowering plants. They do not belong to either the monocots or eudicots but were for a long time lumped together with the eudicots into a well-known group called the dicots. The basal angiosperms are mostly woody plants that produce seeds and flowers. There is roughly 9000 basal angiosperm species currently existing on Earth that can separated into two categories: the ANITA basal angiosperms and the Magnoliids. The majority of species belong to the Magnoliids with only a couple of hundred of the most primitive species being ANITA basal angiosperms. The traits of the basal angiosperms to not tend to fit very well into the characteristic categories used to distinguish between monocots and eudicots. Often basal angiosperms will have what appears to be both monocot and dicot characteristics. For a long time the basal angiosperms and eudicots were clumped together as dicots due to both groups having two embryonic leaves. They also tend to have net-like vein patterns in their leaves as eudicots do, but their pollen only ever has one pore or groove the same as monocots and not three as seen in eudicots. Basal angiosperms have a number of characteristics that show their primitive evolution. They lack any real differentiation between their petal and their sepals and have very little fusion within their floral parts such as petals, stamens and carpels. They tend to have multiple, flattened stamens and multiple carpels, and their fruits are typically single-chambered and dry. Basal angiosperms also have a less advanced vascular system than other angiosperms. Basal angiosperms are found all around the world, with a few exceptions in extreme climates such as Antarctica and the Saharan desert. They enjoy most of their suc Continue reading >>

Basal Ganglia: Definition & Function

Basal Ganglia: Definition & Function

Watch short & fun videos Start Your Free Trial Today An error occurred trying to load this video. Try refreshing the page, or contact customer support. You must create an account to continue watching Start Your Free Trial To Continue Watching As a member, you'll also get unlimited access to over 70,000 lessons in math, English, science, history, and more. Plus, get practice tests, quizzes, and personalized coaching to help you succeed. Coming up next: Blood-Brain Barrier: Definition & Function Log in or sign up to add this lesson to a Custom Course. Custom Courses are courses that you create from Study.com lessons. Use them just like other courses to track progress, access quizzes and exams, and share content. Organize and share selected lessons with your class. Make planning easier by creating your own custom course. Create a new course from any lesson page or your dashboard. Click "Add to" located below the video player and follow the prompts to name your course and save your lesson. Click on the "Custom Courses" tab, then click "Create course". Next, go to any lesson page and begin adding lessons. Edit your Custom Course directly from your dashboard. Name your Custom Course and add an optional description or learning objective. Create chapters to group lesson within your course. Remove and reorder chapters and lessons at any time. Share your Custom Course or assign lessons and chapters. Share or assign lessons and chapters by clicking the "Teacher" tab on the lesson or chapter page you want to assign. Students' quiz scores and video views will be trackable in your "Teacher" tab. You can share your Custom Course by copying and pasting the course URL. Only Study.com members will be able to access the entire course. Create an account to start this course today Try it f Continue reading >>

Ucmp Glossary: Phylogenetics

Ucmp Glossary: Phylogenetics

adaptation -- Change in a organism resulting from natural selection; a structure which is the result of such selection. anagensis -- Evolutionary change along an unbranching lineage; change without speciation. ancestor -- Any organism, population, or species from which some other organism, population, or species is descended by reproduction. basal group -- The earliest diverging group within a clade; for instance, to hypothesize that sponges are basal animals is to suggest that the lineage(s) leading to sponges diverged from the lineage that gave rise to all other animals. binomial nomenclature -- n. A method of identifying and naming organisms using two names. The first name is the genus name, and the second is the species name. Names are usually Latin or Greek in origin. character -- Heritable trait possessed by an organism; characters are usually described in terms of their states, for example: "hair present" vs. "hair absent," where "hair" is the character, and "present" and "absent" are its states. clade -- A monophyletic taxon; a group of organisms which includes the most recent common ancestor of all of its members and all of the descendants of that most recent common ancestor. From the Greek word "klados", meaning branch or twig. cladogenesis -- The development of a new clade; the splitting of a single lineage into two distinct lineages; speciation. cladogram -- A diagram, resulting from a cladistic analysis, which depicts a hypothetical branching sequence of lineages leading to the taxa under consideration. The points of branching within a cladogram are called nodes. All taxa occur at the endpoints of the cladogram. convergence -- Similarities which have arisen independently in two or more organisms that are not closely related. Contrast with homology. crown g Continue reading >>

Basal Lamina: Definition & Function

Basal Lamina: Definition & Function

Watch short & fun videos Start Your Free Trial Today An error occurred trying to load this video. Try refreshing the page, or contact customer support. You must create an account to continue watching Start Your Free Trial To Continue Watching As a member, you'll also get unlimited access to over 70,000 lessons in math, English, science, history, and more. Plus, get practice tests, quizzes, and personalized coaching to help you succeed. Coming up next: Living Systems Requirement for Free Energy and Matter Log in or sign up to add this lesson to a Custom Course. Custom Courses are courses that you create from Study.com lessons. Use them just like other courses to track progress, access quizzes and exams, and share content. Organize and share selected lessons with your class. Make planning easier by creating your own custom course. Create a new course from any lesson page or your dashboard. Click "Add to" located below the video player and follow the prompts to name your course and save your lesson. Click on the "Custom Courses" tab, then click "Create course". Next, go to any lesson page and begin adding lessons. Edit your Custom Course directly from your dashboard. Name your Custom Course and add an optional description or learning objective. Create chapters to group lesson within your course. Remove and reorder chapters and lessons at any time. Share your Custom Course or assign lessons and chapters. Share or assign lessons and chapters by clicking the "Teacher" tab on the lesson or chapter page you want to assign. Students' quiz scores and video views will be trackable in your "Teacher" tab. You can share your Custom Course by copying and pasting the course URL. Only Study.com members will be able to access the entire course. Create an account to start this course tod Continue reading >>

Basal Metabolism: Definition, Factors And Measurement

Basal Metabolism: Definition, Factors And Measurement

Basal Metabolism: Definition, Factors and Measurement In this article we will discuss about the Basal Metabolism:- 1. Definition of Basal Metabolism 2. Conditions for Measurement of Basal Metabolism 3. Factors Influencing 4. Measurement 5. Significance. Conditions for Measurement of Basal Metabolism The total heat produced or the energy spent by the body under conditions to perform minimum possible work is known as basal metabolism. The lowest level of energy production consonant with life is the basal metabolic rate (BMR). 2. Conditions for Measurement of Basal Metabolism: The patient should not take anything by mouth for the past 12 hours. b. Complete mental and physical relaxation. e. Environmental temperature should be between 20C-25C. 3. Factors Influencing Basal Metabolic Rate: The BMR is directly related to the surface area of the subject. Larger the surface area greater would be the BMR. The BMR is inversely proportional to age. Children have larger BMR than adults. Males have higher BMR than females. The BMR of females declines more rapidly between the ages of 5 and 17 than that of males. The BMR of oriental women living in the USA is 10 per cent below the standard BMR of American women of the same age. Persons accustomed to heavy exercise or hard physical work have a higher BMR than those involved in sedentary work. The BMR is decreased in starvation and undernourishment. The BMR is not changed during pregnancy. The higher values of BMR in late pregnancy is due to the BMR of the foetus. The BMR is increased in infectious and febrile diseases. The increase is usually proportional to the rise of the temperature. The BMR is also increased in increased activity of cells and, therefore, it increases in leukemia, cardiac failure, hypertension, polycythemia, dyspnea Continue reading >>

Basal (phylogenetics)

Basal (phylogenetics)

In phylogenetics , basal is the direction of the base (or root) of a rooted phylogenetic tree or cladogram . Clade C may be described as basal within a larger clade D if its root is directly linked (adjacent) to the root of D. If C is a basal clade within D that has the lowest taxonomic rank of all basal clades within D, C may be described as the basal taxon of that rank within D. While there must always be two or more equally basal clades sprouting from the root of every cladogram, those clades may differ widely in rank [n 1] and/or species diversity. Greater diversification may be associated with more evolutionary innovation, but ancestral characters should not be imputed to the members of a less species-rich basal clade without additional evidence, as there can be no assurance such an assumption is valid. [1] [2] [3] [n 2] In general, clade A is more basal than clade B if B is a subgroup of the sister group of A. Within large groups, "basal" may be used more loosely to mean 'closer to the root than the great majority of', and in this context terminology such as "very basal" may arise. A 'core clade' is a clade representing all but the basal clade of lowest rank within a larger clade. A basal group forms a sister group to the rest of the larger clade, such as in the following example: It is assumed in this example that the terminal branches of the cladogram depict all the extant taxa of a given rank within the clade; otherwise, the diagram could be highly deceptive. In phylogenetics, the term basal can be correctly applied to clades of organisms, but not to lineages or to individual traits possessed by the organismsalthough it may be misused in these ways in technical literature. [n 3] A basal group may or may not represent a good analogy for the last common ancestor Continue reading >>

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