Heredity facts for kids
Heredity is the passing of traits (characteristics) from parents to offspring. In biology, the study of heredity is called genetics. With most living things, heredity is analysed by breeding (making crosses), often in a laboratory. But with humans, heredity is studied in other ways. Family pedigrees, identical twins and DNA genome analysis all provide clues.
A trait which may be inherited is heritable; it is inborn or innate.
Images for kids
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DNA structure. Bases are in the centre, surrounded by phosphate–sugar chains in a double helix.
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Aristotle's model of inheritance. The heat/cold part is largely symmetrical, though influenced on the father's side by other factors; but the form part is not.
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An example pedigree chart of an autosomal dominant disorder.
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An example pedigree chart of an autosomal recessive disorder.
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Hereditary defects in enzymes are generally inherited in an autosomal fashion because there are more non-X chromosomes than X-chromosomes, and a recessive fashion because the enzymes from the unaffected genes are generally sufficient to prevent symptoms in carriers.
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On the other hand, hereditary defects in structural proteins (such as osteogenesis imperfecta, Marfan's syndrome and many Ehlers–Danlos syndromes) are generally autosomal dominant, because it is enough that some components are defective to make the whole structure dysfunctional. This is a dominant-negative process, wherein a mutated gene product adversely affects the non-mutated gene product within the same cell.
See also
In Spanish: Herencia genética para niños
