BIOL 1113 Lecture Notes - Lecture 4: Brachydactyly, Epistasis, Polydactyly
Document Summary
Manx cat: mm (tailless), mm (lethal homozygous: polygenic traits. Previous patterns all from alleles of 1 gene. Mutation in one gene leads to build-ups. 1 way that multiple genes affect phenotype. When products of genes work together in same pathway, often see interactions. Epistasis = 1 gene interferes with or prevents expressions of another. Pleiotropy = 1 gene affects several aspects of phenotype. Many taxa include birds recessive in mammals, so only homozygous in mammals, if 1st step in pigment development blocked because no functional enzyme, albino: all other genes in pathway might be normal. Problems with humans: high generation time, low progeny, no controlled crosses. Pedigrees are: starting point for genetic studies, ways to follow heritable traits & diseases, useful for genetic counselling. Pedigree of tool: bigger with more children better, can identify mode of trait inheritance pedigree conventions.
