LIFE 120 Lecture Notes - Lecture 12: Thomas Hunt Morgan, Sickle-Cell Disease, Earlobe
Document Summary
Concept 14. 4 human traits follow mendelian patterns of inheritance. Humans are poor genetic models: generation time is too long, parents produce relatively few offspring, breeding experiments are unacceptable. Pedigree analysis used to trace inheritance patterns of particular traits. 3 generation pedigree analysis for widows" peak. 3rd generation, 2nd generation daughter lacks widows peak. Widows peak trait can be deduced to be dominant. 3rd generation, 1st daughter has attached earlobes. Parents did not express the attached earlobe trait. Practical use in calculating probabilities of inherited traits. Evident only when homozygous for the allele. Carriers - heterozygous with recessive allele - phenotypically. Huntington"s disease: lethal degeneration of the nervous system. Afflicts 1/10,000 in us: no phenotypic effects until age 35, lethal dominant. Thomas hunt morgan (circa 1907: associated a specific gene with a specific chromosome, showed chromosomes are the location of mendel"s herita(cid:271)le fa(cid:272)tors.
