ANTH 1001 Lecture Notes - Lecture 2: Red Blood Cell, Sickle-Cell Disease, Beta Sheet
Document Summary
Polymorphism situation where there exists 2 or more alleles of a gene and at least 2 of the alleles have frequencies greater than or equal to 1%. Polymorphism is explained by natural selection acting on genetic variation, wherein this variation arose by mutation. In humans, approximately 28% of all genes are polymorphic. Balanced polymorphism situation in which there exists 2 or more of a gene, and at least two alleles have frequencies greater than or equal to 1%. The polymorphism is due to heterozygotes having a higher fitness than homozygotes. For example: sickle cell allele and other red blood cell variants, and malaria. Sickle cell hemoglobin (hb) consists of 2 alpha polypeptide strands and 2 beta polypeptide strands. Sickle cell hb is due to a single point mutation in the beta allele, causing a substitution of one amino acid in the beta polypeptide chain.
