The inheritance of biological sex and sex-linked genetic disorders
I can explain how the inheritance of chromosomes determines biological sex in humans, and the inheritance of sex-linked genetic disorders.
The inheritance of biological sex and sex-linked genetic disorders
I can explain how the inheritance of chromosomes determines biological sex in humans, and the inheritance of sex-linked genetic disorders.
Lesson details
Key learning points
- During sexual reproduction, an individual’s biological sex is determined by the chromosomes they inherit.
- In humans, the 23rd pair of chromosomes are sex chromosomes; XX in females and XY in males.
- A gene on the Y chromosome triggers the development of testes, which make male sex hormones (androgens).
- Interpreting, completing and constructing Punnett squares showing the inheritance of human sex chromosomes.
- Some disorders are caused by alleles on the sex chromosomes, so have sex-linked inheritance.
Common misconception
Males only have Y chromosomes, only males inherit sex-linked conditions.
Males have one Y and one X chromosome, males only need one recessive allele to suffer from a sex-linked genetic disorder, whereas females need two and therefore the condition is less common in females.
Keywords
Sexual reproduction - The process of producing offspring where a male and a female provide half the genetic material via gametes.
Biological sex - Male or female as determined by the combination of sex chromosomes inherited (i.e. XX female, XY male).
Sex chromosome - The chromosomes that determine the reproductive and secondary sexual characteristics (i.e. X and Y).
Sex hormone - Chemical messengers, secreted by glands, that help to control the reproductive and secondary sexual characteristics.
Sex-linked disorder - An inherited condition determined by alleles carried by the X or Y chromosome.
Equipment
None required.
Content guidance
- Depiction or discussion of sensitive content
Supervision
Adult supervision recommended
Licence
This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
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Exit quiz
6 Questions
Production of offspring by the fusion of gametes.
In humans, features determined by the 23rd chromosomes.
In humans these can be X or Y.
Chemical messengers that control reproduction and some characteristics