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Homologous sequences are paralogous if they were created by a duplication event within the genome. For gene duplication events, if a gene in an organism is duplicated, the two copies are paralogous. They can shape the structure of whole genomes and thus explain genome evolution to a large extent. Examples include the Homeobox genes in animals.
Homologous recombination, genetic recombination in which nucleotide sequences are exchanged between molecules of DNA; Homologous desensitization, a receptor decreases its response to a signalling molecule when that agonist is in high concentration; Homology modeling, a method of protein structure prediction
Homologous structures - structures (body parts/anatomy) which are similar in different species because the species have common descent and have evolved, usually divergently, from a shared ancestor. They may or may not perform the same function. An example is the forelimb structure shared by cats and whales.
Hox proteins encode and specify the characteristics of 'position', ensuring that the correct structures form in the correct places of the body. For example, Hox genes in insects specify which appendages form on a segment (for example, legs, antennae, and wings in fruit flies), and Hox genes in vertebrates specify the types and shape of ...
In arthropods, an appendage refers to any of the homologous body parts that may extend from a body segment, including antennae, mouthparts (including mandibles, maxillae and maxillipeds), gills, locomotor legs (pereiopods for walking, and pleopods for swimming), sexual organs , and parts of the tail . Typically, each body segment carries one ...
The pattern of limb bones called pentadactyl limb is an example of homologous structures (Fig. 2e). It is found in all classes of tetrapods (i.e. from amphibians to mammals). It can even be traced back to the fins of certain fossil fishes from which the first amphibians evolved such as tiktaalik.
Based on the definition of homology specified above this terminology is incorrect since sequence similarity is the observation, homology is the conclusion. [3] Sequences are either homologous or not. [3] This involves that the term "percent homology" is a misnomer. [4]
Serial homology is a special type of homology, defined by Owen as "representative or repetitive relation in the segments of the same organism." [1] Ernst Haeckel preferred the term "homotypy" for the same phenomenon.