Homology

Homology is a fundamental concept in biology and medicine, referring to the existence of shared ancestry between a pair of structures or genes in different species. A common example of homology is the human arm and the bat wing. Despite their different functions, these structures are homologous, indicating that they evolved from a common ancestor.

Definition

Homology is defined by shared ancestry, not by how similar parts look or how similar they are in function. When two structures in different organisms look or function similarly, but are not the result of shared ancestry, they are called analogous, not homologous.

Types of Homology

There are several types of homology, including:

• Structural Homology: This refers to the similarity in adult morphologies, which is due to inheritance from a common ancestor.
• Genetic Homology: This refers to the similarity in DNA, RNA, or protein sequences due to inheritance from a common ancestor.
• Developmental Homology: This refers to the similarity in embryonic form or developmental processes due to inheritance from a common ancestor.

Homology in Medicine

In medicine, homology is used in genomics and proteomics to predict the function of newly discovered genes and proteins. If a new gene sequence is homologous to a gene that has already been studied, it is likely that the two genes have similar functions.

See Also

• Evolution
• Genetics
• Molecular Biology

References

Homology Resources
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