What is Homology?
In biology, homology refers to the classification of organisms based on the similarity of the structure, development, physiology, and/or genetic sequences between those organisms. [1] Similarities between organisms are ascribed to their common ancestry. [2] Homology can be used to create phylogenetic trees to examine evolutionary history, as well as to applied to comparative genomics. [3] Homologous proteins with high degrees of similarity in their sequences can be predicted to possess similar functions. [3]
An example of structural homology. Each of these species has conserved bone structures, grouped by color, derived from their common ancestor. These structures are retained despite the species' vastly different modern morphology and environments.
Homologs of the Human GLI3 Gene
Homo sapien- Human
Accession number: NP_000159.3
Length: 1580 aa |
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Rattus norvegicus- Rat
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Danio rerio- Zebrafish
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Xenopus Tropicalis-
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Canis lupus familiaris- Dog |
Drosophila melanogaster-
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Caenorhabditis elegans- Nematode |
fasta_model_organisms_final_list.txt | |
File Size: | 17 kb |
File Type: | txt |
Conclusion
Protein BLAST homology searches reveal that GLI3 is well-conserved in vertebrates, which indicates that it is likely an essential gene for survival in some way-- this information supports the existing knowledge of GLI3's role as a developmental gene. [4] Further supporting GLI3's role as an embryonic development gene is the presence of (less-conserved) homologs in invertebrates with bilateral symmetry, but none in organisms without bilateral symmetry.
References
- Pearson, W. R. (2013). An Introduction to Sequence Similarity (“Homology”) Searching. Current Protocols in Bioinformatics, 42(1). doi:10.1002/0471250953.bi0301s42
- Weber, C., Ponting C.P. (2016, April). Genes and Homology. Current Biology, (14) 9:332-333. DOI: https://doi.org/10.1016/j.cub.2004.04.016
- McCune, A. R., & Schimenti, J. C. (2012). Using genetic networks and homology to understand the evolution of phenotypic traits. Retrieved from:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3269019/Homologene: https://www.ncbi.nlm.nih.gov/homologene/1444
- Cheng, F., Ke, X., Lv, M., Zhang, F., Li, C., Zhang, X., . . . Li, S. (2011). A novel frame-shift mutation of GLI3 causes non-syndromic and complex digital anomalies in a Chinese family. 412(11), 1012-1017.
Images
Header: https://www.learnreligions.com/analogous-homologous-structures-4079974
Image 1: https://evolution.berkeley.edu/evolibrary/article/0_0_0/lines_04
Image 2: https://www.1001freedownloads.com/free-vector/free-vector-human-silhouette
Image 3: https://www.shutterstock.com/search/chimpanzee+silhouette
Image 4: https://www.shutterstock.com/search/mouse+silhouette
Image 5: https://www.shutterstock.com/search/rat+silhouette
Image 6: https://www.123rf.com/photo_92871749_stock-vector-zebrafish-illustration-drawing-engraving-ink-line-art-vector-illustration-.html
Image 7: https://www.shutterstock.com/search/frog+silhouette
Image 8: https://www.shutterstock.com/search/dog+silhouette
Image 9: https://www.teepublic.com/phone-case/3772142-common-house-fly-silhouette
Image 10: https://stock.adobe.com/search?k=acanthocephalan
Image 1: https://evolution.berkeley.edu/evolibrary/article/0_0_0/lines_04
Image 2: https://www.1001freedownloads.com/free-vector/free-vector-human-silhouette
Image 3: https://www.shutterstock.com/search/chimpanzee+silhouette
Image 4: https://www.shutterstock.com/search/mouse+silhouette
Image 5: https://www.shutterstock.com/search/rat+silhouette
Image 6: https://www.123rf.com/photo_92871749_stock-vector-zebrafish-illustration-drawing-engraving-ink-line-art-vector-illustration-.html
Image 7: https://www.shutterstock.com/search/frog+silhouette
Image 8: https://www.shutterstock.com/search/dog+silhouette
Image 9: https://www.teepublic.com/phone-case/3772142-common-house-fly-silhouette
Image 10: https://stock.adobe.com/search?k=acanthocephalan
This web page was produced as an assignment for Genetics 564, an undergraduate capstone course at UW-Madison.