<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> <P> Humans have a total of 46 chromosomes, but there are only 22 pairs of homologous autosomal chromosomes . The additional 23rd pair is the sex chromosomes, X and Y . If this pair is made up of an X and Y chromosome, then the pair of chromosomes is not homologous because their size and gene content differ greatly . The 22 pairs of homologous chromosomes contain the same genes but code for different traits in their allelic forms since one was inherited from the mother and one from the father . So humans have two homologous chromosome sets in each cell, meaning humans are diploid organisms . </P>

Place the characteristic with the correct corresponding structure homologous chromosomes