Genetics and Heredity Part III

Every path has its puddle.

English proverb

Today’s Agenda

Dihybrid crosses Incomplete dominance Codominance Polygenic

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Obj. 9 Incomplete Dominance Definition:

A condition in which a trait in an individual is intermediate between the phenotype of the two parents because the dominant allele is unable to express itself fully.

Example of Incomplete Dominance:

Red snapdragon X white snapdragon

All offspring are pink snapdragons

Codominance

Definition: a condition in which both alleles for a gene are fully expressed.

Ex. Blood Types

Polygenic

Definition: a characterisitc of an organisms that is determined by many genes

Ex. Eye color, height, weight

Multiple Alleles

Genes with three or more alleles

Example: Blood groups A = AO, AA B = BO, BB AB = AB O = OO

Practice Problems