HMB265H1 Lecture Notes - Lecture 12: Siamese Cat, Zygosity, Melanin

• School: UTSG
• Department: Human Biology
• Course: HMB265H1
• Professor: Maria Papaconstantinou

Document Summary

Ch 2: 34-36; 51-56: ch 12: 410-411. Quantitative genetics - intro: continuous variation, additive inheritance, environmental effects, normal distributions. Review and introduction: frequency histograms are most useful for plotting phenotypic results. Most traits are thought to involve this. Prime example is flower colour where colour becomes a mix. Results in progeny with phenotypic ratio of 1:2:1: most of nature does not follow full mendelian traits. Simple one-locus example: phenotypic effects can be additive. Phenotypic effects would be the same as the genotypic. One allele can influence colour, for example - higher presence of one allele will intensify the colour. Result is a gradient across the phenotypes: below is a histogram exhibiting this. Note that mendelian genetics are still being applied. Dihybrid and two loci: consider dihybrid cross with additive effects - locus a and b, by additive effects, for both loci - the second allele has an effect of 1. Assuming that locus has additive effects - key difference.