HMB265H1 Lecture Notes - Lecture 12: Null Allele, Siamese Cat, Frequency Distribution

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

Document Summary

Hmb265: lecture 12 - human & general genetics. Phenotypes that have vast variety and distribute continuously. F2 generation has large and tiny fruits. Situations where have dominant and recessive alleles. Progeny either resemble one parent or the other. But this not the only mode of inheritance. Get heterozygote that has different phenotype from each parent. Identify heterozygote by phenotype which we couldn"t do when just dominant and recessive traits. When a phenotype varies continuously with levels of protein function, incomplete dominance results. Homozygous recessive = null mutation = no pigment = white flower. Wt = 2 copies of wt gene each generating enzyme. Phenotype is dependent on copy number of the allele. Dependent on levels of the functional protein being produced. Heterozygote displays different phenotype that can identify than both parents. Defect in gene that generates receptor = levels of cholesterol is really high. Homozygotes for mutant gene die at early age. Concentration of cholesterol in blood is around 200.