A pair of similar chromosomes is called homologous chromosomes. Homologous chromosomes are the same size and shape, and they contain the same genes in the same order, but there may be variation between them, resulting in different alleles. Homologous chromosomes are paired chromosomes, and they are comprised of one paternal chromosome and one maternal chromosome. During meiosis, homologous chromosomes line up and recombination occurs between them, resulting in gametes with unique combinations of alleles on each chromosome and therefore unique individuals.