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The term "homology" was first used in biology by the anatomist Richard Owen in 1843 when studying the similarities of vertebrate fins and limbs, defining it as the "same organ in different animals under every variety of form and function", [6] and contrasting it with the matching term "analogy" which he used to describe different structures ...
The structure of immunoglobulin G-binding bacterial proteins A and H do not contain any sequences homologous to the constant repeats of IgG antibodies, but they have similar functions. Both protein G, A, H are inhibited in the interactions with IgG antibodies (IgGFc) by a synthetic peptide corresponding to an 11-amino-acid-long sequence in the ...
Functionally similar features that have arisen through convergent evolution are analogous, whereas homologous structures or traits have a common origin but can have dissimilar functions. Bird, bat, and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions.
They may or may not perform the same function. An example is the forelimb structure shared by cats and whales. Analogous structures - structures similar in different organisms because, in convergent evolution, they evolved in a similar environment, rather than were inherited from a recent common ancestor. They usually serve the same or similar ...
Analogical models, also called "analog" or "analogue" models, seek the analogous systems that share properties with the target system as a means of representing the world. It is often practicable to construct source systems that are smaller and/or faster than the target system so that one can deduce a priori knowledge of target system behaviour.
Bottom: in a separate species , a gene has a similar function (histone-like nucleoid-structuring protein) but has a separate evolutionary origin and so is an analog. Sequence homology is the biological homology between DNA , RNA , or protein sequences , defined in terms of shared ancestry in the evolutionary history of life .
In cases where the similar structures serve different functions in adults, it may be necessary to trace their origin and embryonic development. A similar developmental origin suggests they are the same structure, and thus likely derived from a common ancestor. When a group of organisms share a homologous structure that is specialized to perform ...
Although structures commonly regarded "vestigial" may have lost some or all of the functional roles that they had played in ancestral organisms, such structures may retain lesser functions or may have become adapted to new roles in extant populations. [4] It is important to avoid confusion of the concept of vestigiality with that of exaptation ...