But in males ZZ , two alleles work together to determine feather color according to their dominance. When the male and female gametes fuse during sexual reproduction, a new offspring having 46 chromosomes is produced. There are 23 pairs of chromosomes of which 22 pairs are called autosomes and the 23rd pair is called allosome or sex chromosomes Autosomes Autosomes are homologous pairs, which transfer genetic information from the parents to the offspring. Through this functioning, double-strand breaks can be repaired and DNA can function normally. And males make sperm, which can have an X or a Y. One gene on the Z chromosome affects feather color ; three different alleles make feathers blue, ash-red, or brown. An egg plus an X-containing sperm will make a female offspring, and an egg plus a Y-containing sperm will make a male offspring. So the new daughter cells get a complete copy of chromosomes containing the genetic information from the parent cell. The X and Y chromosomes, however, have different genes. Unusual combination of allosomes result in disorders like colour blindness, haemophilia, Fragile X syndrome. This mixing of maternal and paternal traits is enhanced by crossing over during meiosis, wherein lengths of chromosomal arms and the DNA they contain within a homologous chromosome pair are exchanged with one another. Male gametes are of two kinds, one kind with 22 autosomes and one X chromosome, and the other kind with 22 autosomes and one Y chromosome. The differences in sex chromosomes between males and females leads to specific inheritance patterns for sex-linked genes. The process of meiosis I is generally longer than meiosis II because it takes more time for the chromatin to replicate and for the homologous chromosomes to be properly oriented and segregated by the processes of pairing and synapsis in meiosis I. Centromere placement can be characterized by four main arrangements, consisting of being either metacentric, submetacentric, telocentric, or acrocentric.