What the . . . Punnett!!!• You and 1 partner:

1) Come up with a hypothesis of how this could be (“if” and “then”)

2) Make a punnett square to support your hypothesis

3) Be able to defend your hypothesis

Beyond Mendel

Codominance and Incomplete Dominance

Mmmendel!

•Polygenic InheritancePolygenic Inheritance

•Many genes code for that 1 trait

•Ex: • Eye color, • height, and • skin color

Order of dominance: brown > green > blue.

• Multiple AllelesMultiple Alleles

•If there are more than two different alleles for that genein the gene pool.

•Example: ABO blood type (IA , IB and i).

Incomplete Dominance

• Definition: A situation in which one allele is not completely dominant over another.

• The heterozygous phenotype is somewhere in between the two homozygous phenotype.

Tricks of Incomplete Dominance• 1) Letters we use are both capitals because

both are dominant!

• 2) The offspring show a third phenotype

• 3) The offspring show a blending of the parental traits

BlahBlahBlah!!!• Question: A cross between a blue

blahblah bird & a white blahblah bird produces offspring that are silver.  The color of blahblah birds is determined by just two alleles. – 1) What are the genotypes of the parent

blahblah birds in the original cross?  – 2) What is/are the genotype(s) of the silver

offspring?

– 3) What would be the phenotypic ratios of offspring produced by two silver blahblah birds?

Codominance

• Definition: Situation in which both alleles of a gene contribute to the phenotype of an organism– Often produces offspring known as “eminette”

Sickle Cell Anemia• Codominant

• A=normal, S=Sickle

• AA = Normal – Malaria

• AS = Hetero – No Malaria

• SS = Sickle – No Malaria