BIOLOGY 2C03 Lecture Notes - Lecture 2: Mendelian Inheritance, Human Height, Probability Distribution
13 Mar 2018
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Document Summary
Discontinuous characteristics, exhibits only a few distinct phenotypes. May be determined by one gene with many alleles or multiple genes. Continuous characteristics, continuous variation within a range of phenotypes. Often affected by variation in the environment, even one gene can display this. Phenotype: a quantitative measurement (numbers) - 22 cm, 22. 5 cm, etc. Continuous variation - can assume any value between 2 values (boundaries) - number of phenotypes limited by the resolution of the measurement tool. Most common type of quantitative trait e. g. human height, seed weight, milk production. Threshold characteristics - not continuous, either present or absent, determined by multiple factors e. g. human cancer - present or absent, many contributing factors. Yyrr x yyrr (yellow, round x green, wrinkled) Quantitative characteristic - polygenic inheritance in wheat (nilsson-ehle) P plants with white kernels x plants with purple kernels. F2 1/16 purple, 4/16 dark red, 6/16 red, 4/16 light red, 1/16 white.
