Applications of Mendel. Dominant/Recessive For every gene/characteristic an individual possesses two inherited copies (alleles) One maternal, one paternal.

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

Dd 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