Definition of Homologous
Homologous in molecular biology is defined as the two genes that have been derived from the common ancestor. These two genes have an almost similar sequence of nitrogenous bases (A, G, C, U) in their DNA. It can also be taken in terms of homologous chromosomes which are defined as the paired chromosomes. These chromosomes have the same location of the centromere, have the same sequence of genes and the same loci.
The length of these chromosomes is also the same but the alleles present on the loci may be different. The genetic material of a human is composed of 23 pair of homologous chromosomes out of which 22 pairs are autosomal and the 1 pair which is sex chromosome may be homologous in case of XX (female) or heterologous in case of XY (male).