Genes for the same trait on a homologous pair of chromosomes are called alleles . Autosomes are chromosomes that carry information for non-sex characteristics. The remaining 1 pair are called the sex chromosomes , which carry sex linked genes and dertemine an individual's sex. These chromosomes are labeled XX in the female and XY in the male. Interphase I precedes meiosis.
Chromosomes replicate as in mitosis.
Each duplicated chromosome consists of two identical sister chromatids attached at their centromeres. Centriole pairs in animal cells also replicate into two pairs. This cell division segregates the two chromosomes of each homologous pair and reduces the chromosome number by one-half. This is a longer and more complex process than prophase of mitosis. Since each chromosome has two chromatids, each homologous pair in synapsis appears as a complex of four chromatids or a tetrad .