BIO 111 Lecture Notes - Lecture 3: Mendelian Inheritance, R.W.D. Molenbeek, Epistasis
Document Summary
Bio 111 - lecture #3 - mendelian genetics (cont. ) Incomplete dominance: genes that exhibit incomplete dominance can control some phenotypes. The dominant allele does not fully have dominance. Example: snapdragons rr x rr yields 1 rr red: 2 rr pink: 1 rr white. Codominance: alleles that exhibit codominance control some phenotypes. The i gene encodes an enzyme that attaches sugars to proteins on the surface of red blood cells. Ia, ib. and io alleles exist in humans. The ia and ib alleles encode an enzyme but the enzyme attaches different sugars. The io allele encodes an inactive enzyme. The alleles are codominant to each other. Quantitative traits: phenotypes that are controlled by multiple genes giving rise to a continuous distribution of values. Epistasis: the phenotype expression of one gene is controlled by another gene. Widespread epistasis genes occurs in plants that exhibit hybrid rigor. Example: coat color in a labrador is controlled by 1 gene/allele that makes hair pigments.