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Homologous   [ Biology ]

Dictionary of botanic terminology - index of names
 

Synonyms: Homologue, Homolog Homologic, Homological
Antonyms: Analogous, Autologous, Heterologic, Heterological, Heterologous
Noun: Homology
     
  Corresponding or similar in position or structure or function or characteristics  
     
Compare with: Analogous
(1) Homologous    [  Biology  ]
     
  Of anatomical structures within different organisms derived from the same structure of a common ancestor.  

From the Greek homos = same, and logos = word, hence a part with similar morphology but different function.

Referring to anatomical structures that show a fundamental similarity within different organisms because originated from a structure or trait of a common ancestry rather than a product of a similar environment (compare: Analogous, Homoplastic).
Homologous structures in related species have the same evolutionary origin although their functions may differ widely. The structures in their current forms may not necessarily perform the same functions in each organism, nor perform the functions it did in the common ancestor. They may even have become completely unused and therefore vestigial.         "the wing of a bat, the flippers of a seal and the arm of a man are homologous"

(2) Homologous    [ Genetics ]
     
  a) Of a chromosome having the same morphology and linear sequence of gene loci as another chromosome. Containing the same linear gene sequences, each derived from one parent.
b) Of a genes in a genome sharing a similar DNA base sequence with an other genes because they arose by duplication of an ancestral gene..
 
(3) Homologous    [ Chemistry ]
     
  Of organic chemical compounds belonging to the same type or series; corresponding in composition and properties.  

In molecular biology, often "homologous" is used loosely to mean similar.

 

 

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