HMB265H1 Lecture Notes - Lecture 12: Environmental Modification Convention, Melanin, Allele

• School: UTSG
• Department: Human Biology
• Course: HMB265H1
• Professor: Maria Papaconstantinou

Document Summary

Slide 1 - 22: what is a quantitative trait: phenotypic variation does not always appear discrete (qualitative), but can be discontinuous (quantitative) (as is the case with height, incomplete dominance (additive inheritance) For each dose of an allele, there is a different phenotype. It is important to note that additive inheritance can be and is the result of multiple loci, but the examples only show 1 loci (a) [with multiple alleles of different additive values] for simplicity. Most quantitative traits show incomplete dominance and thus additive inheritance. Additive inheritance shows a normal distribution , showing that the distribution is continuous (not discrete) 2 hypotheses for the origin of a quantitative trait. A quantitative trait can be explained on the basis of : the segregation of alleles at many loci, where the loci have small, equal additive effects, a few genes with large additive effects. Quantitative traits: are said to be polygenic or multifactorial!