7. p. 264X-linked Genes and Sex Chromosomes
- Philip Meneely, Philip MeneelyHaverford College
- Rachel Dawes Hoang, Rachel Dawes HoangHaverford College
- Iruka N. OkekeIruka N. OkekeUniversity of Ibadan, Nigeria
- , and Katherine HestonKatherine HestonHaverford College
Abstract
This chapter discusses the presence or absence of sex chromosomes that determines the sex of the individual. It explains that sex is defined by having two different sex chromosomes or being heterogametic, such as human males that are XY. It also looks at the consequences for the inheritance of genes on the X chromosome, wherein different patterns of inheritance are observed for X-linked traits in males and females. The chapter reviews the non-disjunction of the sex chromosomes or the failure to segregate normally during meiosis that results in individuals with unusual numbers of X or Y chromosomes, illuminating some of the different modes of sex determination in some species. It defines sexual dimorphism, wherein different species exhibit physical differences between the sexes in anatomy, physiology, coloration, and behaviour.