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

Testosterone

• 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…