BIOLOGY 2C03 Lecture Notes - Lecture 4: Quantitative Genetics, Probability Distribution, Frequency Distribution
23 Apr 2016
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Continuous variation: pheno variation distributed across a range of values in an uninterrupted continuum. Human height has multi traaits that varies continuously along a scale of measurments. Genetic potential is the height obtained if the child grows under ideal conditions. Major genes: genes that influence the phenotype more strongly eg. in eye colour there is oca2. Modifier genes: have a minor effect on the phenotype. Number of phenotype categories for a polygenic trait produced by segregation of additive alleles for n number of genes is calculated 2n + 1. A frequency distribution of values of eh trait on a quantative scale. Variance: s^2: the spread of the distribution around the mean. It will be small if all of the observations are close to the mean: sum of each individual value minus the mean squared, divided by the degrees of freedom.
