Applications of Mendel

Dominant/Recessive For every gene/characteristic an individual possesses two inherited copies (alleles) One maternal, one paternal EXAMPLE: Inherited attached earlobes allele from mom, unattached earlobes allele from dad In cases of Mendellian inheritance, allele is dominant, one is recessive

Which is dominant? EXAMPLE: Attached vs. Detached earlobes Possible gene combinations: 2 attached genes (dd) 1 attached, 1 detached (Dd) 2 detached genes (DD)

Predicting inheritance… Punnett squares

Punnett Square Dd DD d d

Practice with Mendel 1.Cross a pea plant with round peas (Rr) with a pea plant with wrinkled peas(rr) 2.Cross a pea plant with green pods (Gg) with itself (Gg)

Genotype/Phenotype Genotype: DD, Phenotype: Detached earlobes Genotype: dd, Phenotype: Attached earlobes Genotype: Dd, Phenotype: Detached Earlobes Genotype is actual gene combination Phenotype is the observed trait

Genotype/Phenotype Mary has the phenotype brown eyes and curly hair. Can we know her genotype based on this information? Mary has the genotype Bb for eye color and CC for hair curl. B is for dominant brown, C is for dominant curly. Can we know her phenotype based on this information?

Homozygous/Heterozygous Homo=same Hetero=different Heterozygous means two different alleles Ex: earlobes (Dd) Homozygous means two of the same allele Ex: earlobes (DD) or (dd)

George has freckles. Can you tell if he is homozygous dominant or heterozygous dominant for this trait? George is heterozygous for freckles. Freckles are a dominant trait. Can you tell his phenotype given this information?

Wildtype/Mutant Wildtype: most commonly occurring in nature Mutant: A deviation from the wildtype, a less common allele