HMB265H1 Lecture Notes - Lecture 6: Dihybrid Cross, Zygosity, Phenotype

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

Document Summary

Hmb265: lecture 6 - extensions of mendelian genetics part 2 (sept. 26) Experiments: species of fish that lives in caves. Ancestors had sight, but over many years, fish that lived in caves became bline. Cross cave 1 and cave 1, f1 all blind. Cross cave 1 and cave 2, f1 can see. Cross cave 1 and cave 3, f1 can see. One allele providing what the other is lacking. Accumulated mutations in genes that controlled eye development. Fish from different caves had mutations in different genes controlling eye development. Deficiencies in one lineage compensated for deficiencies in other lineage. Different null mutations in same gene should give same phenotype. Mutations in same gene can give rise to same phenotype but mutations in different genes might also give rise to same phenotype. Homozygous mutations in coding sequence or promoter, end up with same phenotype = no function. Recessive genotypes result in same mutant phenotype. Say wt allele is dominant to mutant.