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Genetic variation and genetic disorders


Polydactylypolydactyly: A condition in which there are more than five fingers or toes on a hand or foot. is an inherited condition in which a person has extra fingers or toes. It is caused by a dominant allele of a genegene: The basic unit of genetic material inherited from our parents. A gene is a section of DNA which controls part of a cell's chemistry - particularly protein production.. This means it can be passed on by just one parent if they have the disorder.

The genetic diagram shows how this can happen.

Polydactyly allele chart

Offspring need to carry just one dominant allele from their parents to inherit the polydactyl condition

Note that if you are doing the Foundation tier paper you are expected to be able to interpret genetic diagrams. If you are doing the Higher tier paper, you are expected to be able to draw genetic diagrams for any combination of dominant and recessive alleles.

Back to Cell division and inheritance index

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