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homology
homologous
homologous 1. (in biology) Describing a character that is shared by a group of species because it is inherited from a common ancestor. Such characters, called
homologies, are used in
cladistics to determine the evolutionary relationships of species or higher taxa. They are divided into two types: a
shared derived homology (see
apomorphy) is unique to a particular group and may be used to define a
monophyletic group; a
shared ancestral homology (see
plesiomorphy) is not unique to the group, or may not be exhibited by all descendants of the ancestor in which it arose (see
paraphyletic). Even though homologous features share the same evolutionary origin, they may have developed different functions. For example the wings of a bat, the flippers of a dolphin, and the arms of a human are homologous organs, having evolved from the paired pectoral fins of a fish ancestor. Compare
analogous.
2. (in molecular biology) Describing sequences of nucleotides (or amino acids) at corresponding sites of different nucleic acids (or proteins) that show similarity because the molecules are descended from a common ancestral molecule. The term is sometimes used more loosely, but incorrectly, to describe sequences that are merely similar, when no evolutionary relationship is implied or can be established. See
orthologous;
paralogous. See also
conserved sequence.
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Flexible mapping of homology onto structure with Homolmapper.
Magazine article from: BMC Bioinformatics; 4/11/2007; ; 700+ words
; ...determined structure but with varying homology to a protein of known structure. When...biochemical experiments. For example, homology modeling can be used to build a model...structure. First introduced in 1969 [1], homology modeling has become a more commonly applied...
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Numerical Investigation of Sequence Dependence in Homologous Recognition: Evidence for Homology Traps
Magazine article from: Biophysical Journal; 6/1/2005; ; 700+ words
; ...recombination, known as the search for homology, a single-stranded DNA coated by RecA...and pair. We designed a model for the homology search between short molecules, and...energy parameters. This mechanism of homology trapping could have a strong biological...
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Homology modelling of protein-protein complexes: a simple method and its possibilities and limitations.(Research article)(Report)
Magazine article from: BMC Bioinformatics; 10/9/2008; ; 700+ words
; ...attractive possibility is to perform homology modelling, and exploit the ever-growing...protein-protein complexes [16, 18]. Homology modeling of a protein-protein complex...possibilities and limitations of a simple homology modelling procedure for protein-protein...
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Homology-Modeled Structure of the Yeast Mitochondrial Citrate Transport Protein
Magazine article from: Biophysical Journal; 8/1/2004; ; 700+ words
; ABSTRACT We have used homology modeling to construct a three-dimensional...Superposition of the backbone traces of the homology-modeled CTP onto the crystallographically...72-2.06 [Angstrom]). The homology-modeled CTP is consistent with our...
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The question of cotyledon homology in angiosperms.
Magazine article from: The Botanical Review; 10/1/1998; ; 700+ words
; ...1997). III. The Question of Cotyledon Homology A major question, rarely discussed...first examine the fundamental question of homology. Homologous features share an underlying...methodology has reaffirmed the significance of homology in phylogenetic hypotheses (Patterson...
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Strategies for development of functionally equivalent promoters with minimum sequence homology for transgene expression in plants: Cis-elements in a novel DNA context versus domain swapping1
Magazine article from: Plant Physiology; 6/1/2003; ; 700+ words
; ...transgene inactivation due to promoter homology. As a way to circumvent this problem...equivalent but have a minimum sequence homology. Such promoters can be generated by...synthetic promoters with minimum sequence homology and with expression levels comparable...
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Improved homology-driven computational validation of protein-protein interactions motivated by the evolutionary gene duplication and divergence hypothesis.(Methodology article)(Report)
Magazine article from: BMC Bioinformatics; 1/19/2009; ; 700+ words
; ...applied this 'all-inclusive' approach to homology-based PPI validation [8, 22, 23...experimentally determined PPIs. Figure 1: Homology-Based PPI Validation . Concept of homology-based PPI validation: based on an experimentally...
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A discriminative method for protein remote homology detection and fold recognition combining Top- n -grams and latent semantic analysis.(Research article)
Magazine article from: BMC Bioinformatics; 12/1/2008; ; 700+ words
; ...structural classes by means of homologies. Most methods can detect homologies at high levels of sequence similarity, while accurately detecting homologies at low levels of sequence similarity (remote homology detection) is still a challenging...
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Evolution of development of the vertebrate dermal and oral skeletons: Unraveling concepts, regulatory theories, and homologies
Magazine article from: Paleobiology; 10/1/2002; ; 700+ words
; ...providing no means of identifying homologies beyond this. The lepidomorial...theory in its ability to trace homology through the evolution of development...criteria proposed to identify homology between scales-either within...is no means of identifying homology between individual elements...
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On the Accuracy of Homology Modeling and Sequence Alignment Methods Applied to Membrane Proteins
Magazine article from: Biophysical Journal; 7/15/2006; ; 700+ words
; ...investigate the extent to which techniques for homology modeling that were developed for water...assessment of current strategies for homology modeling of membrane proteins and introduce...proteins. This analysis indicates that homology modeling is at least as applicable to...
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Homology
Book article from: Animal Sciences
Homology The term "homology" was defined in 1843 by Richard Owen, a noted British paleontologist...various taxa derives from their common origin in a shared ancestor. Homology may be based on: similarities in structure, or how an organ is...
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Serial Homology
Book article from: Animal Sciences
Serial Homology As organisms evolve, their existing...it somewhere else is known as serial homology . As evolution is necessarily a stepwise...organismal evolution. As such, serial homology is a widespread evolutionary tactic that...
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homology
Book article from: The Columbia Encyclopedia, Sixth Edition
homology , in biology, the correspondence between structures of different species that is attributable to their evolutionary descent from...
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Systematics, Molecular
Book article from: Plant Sciences
...limitations. One limitation to morphology in plants is homology. Homology assumes that two similar structures have the same...ancestor and was passed down to its descendants. Homology in plant morphology is frequently very difficult to...
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Comparative Biology
Book article from: Animal Sciences
...Function is not a reliable indicator of homology because similar functions may be formed...structure). The criteria differ for judging homology in other types of traits. For example, judging homology in behavioral traits would require examination...
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