BIOLOGY 171 Lecture Notes - Lecture 8: Single-Nucleotide Polymorphism, Quantitative Trait Locus, Pea
5 Oct 2016
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Discrete traits: aka mendelian traits; have only 1 or 2 expressed phenotypes. Examples: flower color in peas, yellow or green pea pods, abo blood types, eye color in fruit flies. Polygenetic inheritance: term used to talk about a trait influenced by 2+ gene (complex traits which are influenced by 2+ genes and the environment) and how they are inherited. Results in a continuous phenotypic distribution versus 2 phenotypes with complete dominance or 3 phenotypes with incomplete or codominance. This is represented in a bell curve like the one to the right. Examples: height in humans, hair color, skin color, body weight, seed weight in peas. Example cross using polygenic inheritance in wheat kernel color. P generation: true-breeding white x true-breeding dark red. Continuous distribution of phenotypes suggests polygenic inheritance (extremes are either of the parent phenotypes) *we actually know that there are 3 genes that determine wheat kernel color.
