BIOLOGY 171 Lecture Notes - Lecture 8: Quantitative Trait Locus, Human Hair Color, Bipolar Disorder
18 Feb 2019
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Document Summary
Discrete (or mendelian): traits that are in uenced by one gene: phenotypes fall into a few distinct classes. Polygenic: traits that are in uenced my 2 or more gennes: phenotypes display a (bell-shape) normal distribution. Example of discrete traits: abo blood types, red/ green color blindness, red vs white eye color in fruit ies. Flower color, seed color, seed shape in sweet peas. Example of polygenic traits (most common: height in humans, body weight eye color skin color, hair color, risk of bipolar disorder. Wheat kernel color is a complex trait risk of heart disease. If this was a discrete trait inn f2 generation, we would see 3:1 or 1:2:1 phenotypical rations. In polygenic inheritance we see a continuous distribution of phenotypes in the. F2 generation: we see ones that look like true breeding, and like f1"s but also colors in the middle and more extreme.
