HMB265H1 Lecture 12: Introduction to Quantitative Genetics (Lecture 12)
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HMB265H1 Full Course Notes
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Phenotypic variation doesn"t always appear discrete" qualitative but rather continuous: many traits seem quantitative in nature, continuous variation frequently with a normal distribution (bell curve) Threshold trait" categorical traits that do not show simple inheritance individuals with a certain number of risk factors will exceed a threshold" and develop a disease. A trait displaying simple dominance mode of inheritance. Heterozygous at locus a: each individual has a locus a, genotypic ratio of 1 aa: 2 aa : 1 aa. It is hard to distinguish genotype at phenotypic level. This is a frequency histogram: with simple dominance mode of inheritance, a trait measure is composed of different genotypes when looking just at a trait" it is easy to confound genotypes. Anything with a will have the trait, and aa will not have the trait: but it is hard to tell the exact genotype from trait is it aa or aa.
