GENETIC TOPICS NON-MENDELIAN TRAITS
POLYGENIC TRAITS Polygenic traits, or continuous traits, are governed by alleles at two or more loci, and each locus has some influence on the phenotype. Hair, eye and skin color are polygenic traits
POLYGENIC TRAITS CONT….. Stature, shape of face, fingerprint patterns are polygenic traits Most can be measured, i.e. height in feet and inches or meters and centimeters
X CHROMOSOME INACTIVATION X chromosome inactivation occurs early during development – around 24 cell Thus, females embryos have two active X chromosomes until one is inactivated
X INACTIVATION Because of X-inactivation every female is a mosaic of cell lines with different active X chromosomes
GENE EXPRESSION BASED ON ENVIRONMENT