Short notes
Mutation.
Definition
This is a phenomenon where the expression of a gene depends on which parent it was inherited from. Certain genes are "silenced" via DNA methylation during gamete formation.
Example / case study
- Phenylketonuria (PKU). A mutation on Chromosome 12 leads to an inability to metabolize phenylalanine, which subsequently causes intellectual disability, skin pigmentation loss, and neurological issues.
- HLA (Human Leukocyte Antigen) genes. On Chromosome 6, genes A, B, and C are linked and almost always inherited as a single unit.
- Prader-Willi Syndrome occurs if a specific segment of Chromosome 15 is deleted from the paternal side, while Angelman Syndrome results if the same segment is deleted from the maternal side.
Thinkers
- Marriage as Exchange: Lévi-Strauss used the Purum case to argue that kinship is fundamentally a system for the reciprocal exchange of women between groups, which acts as a form of social communication.
- Challenge to Descent Primacy: While British anthropologists like Radcliffe-Brown emphasized descent groups (lineages/clans) as the primary basis of social structure, the Purum system proved that marriage alliances are equally fundamental.