ANT202H5 Lecture Notes - Lecture 4: Gregor Mendel, Blending Inheritance, Zygosity
Document Summary
Mendel + darwin = modern synthesis of evolution. Crossed different purebred pea plants: types and proportions of hybrids, test the idea of blending inheritance. Phenotype observable appearance of trait in organism. Allele: one member of gene pair that codes for different versions of trait: can be dominant or recessive. Allele combinations: homozygous = both alleles at given locus identical, heterozygous = differing alleles at given locus, genotypic ratio. Dominant allele that masks effect of other in heterozygous genotype: always phenotypically expressed. Recessive allele whose effect is masked by other in heterozygous genotype: only expressed in the homozygous form. Combo of 2 different alleles = 4 phenotypic outcomes. Dominance heterozygote same phenotype as of one of the homozygotes. Incomplete dominance heterozygote has different phenotype than any homozygotes: neither allele masked by other, more like blending. Codominance = both alleles affect phenotype of heterozygous genotype: neither dominant over other, both alleles are expressed but not they are not blended.
