The methods of detecting gene homology

Abstract

Hereditary variations which are phenotypically similar are not necessarily based upon homologous changes in genetic material. Genes (and mutations of the genes) may be considered as homologous (that is stemming from the common ancestral gene) if they have similar structures and control similar functions. Cytological, cytogenetical and some biochemical methods reveal general similarities between karyotypes, genomes, particular chromosomes and chromosomal segments of different species. Homology of the genes of different species may be detected on the basis of the results of genetic analysis and precise biochemical methods of studying primary structure of RNA and proteins. Genetic analysis reveals the details of genetic determination of characters (the number of genes), the mode of action and interaction of the genes, the particular characteristics of detectable multiple series of alleles and pleiotropy in gene effect as well as localization of the genes in linkage maps. The similarity between different species in all these characteristics of the gene(s), determining similar characters may be taken as good evidence of the homology of the gene(s).