<P> Early in the 1900s William Bateson and Reginald Punnett were studying genetic inheritance and they noted that some combinations of alleles appeared more frequently than others . That data and information was further explored by Thomas Morgan . Using test cross experiments, he revealed that, for a single parent, the alleles of genes near to one another along the length of the chromosome move together . Using this logic he concluded that the two genes he was studying were located on homologous chromosomes . Later on during the 1930s Harriet Creighton and Barbara McClintock were studying meiosis in corn cells and examining gene loci on corn chromosomes . Creighton and McClintock discovered that the new allele combinations present in the offspring and the event of crossing over were directly related . This proved interchromosomal genetic recombination . </P> <P> Homologous chromosomes are chromosomes which contain the same genes in the same order along their chromosomal arms . There are two main properties of homologous chromosomes: the length of chromosomal arms and the placement of the centromere </P> <P> The actual length of the arm, in accordance with the gene locations, is critically important for proper alignment . Centromere placement can be characterized by four main arrangements, consisting of being either metacentric, submetacentric, telocentric, or acrocentric . Both of these properties are the main factors for creating structural homology between chromosomes . Therefore, when two chromosomes of the exact structure exist, they are able to pair together to form homologous chromosomes . </P> <P> Since homologous chromosomes are not identical and do not originate from the same organism, they are different from sister chromatids . Sister chromatids result after DNA replication has occurred, and thus are identical, side - by - side duplicates of each other . </P>

Homologous chromosomes have the exact same nucleotide sequence