The role of chromosomes and hormones


The role of chromosomes and hormones in sex and gender

The role of chromosomes

  • Chromosomes are made from DNA
  • Genes are short sections of DNA that determine the characteristics of a living thing
  • There are 46 chromosomes in the human body arranged into 23 pairs- with the 23rs pair determining biological sex
  • Females-**
  • Males-XY
  • All normal egg cells have an X chromosome
  • Half the sperm carry an X chromosome and half carry a Y
  • The Y chromosome carries a gene called the sex determining region Y (SRY)
  • The SRY gene causes testes to develop in an XY embryo, which produce androgens: male sex hormones
  • Androgens cause the embryo to become a male

The role of hormones

  • Chromosomes initially determine a person's sex but most gender development actually comes through the influence of hormones
  • Prenatally, hormones act upon brain development and cause the development of reproductive organs
  • At puberty, a burst of hormonal activity triggers the dev of secondary sexual characteristics
  • Males and females produce many of the same hormones but in different concentrations


  • A male hormone which controls the dev of male sex organs, which begins to be produced at around 8 weeks of foetal dev
  • Linked to aggression
  • Nanne Van de Poll showed…


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