Genetics After Mendel Complete Incomplete CoDominance Complete Dominance

Genetics After Mendel Complete, Incomplete & Co-Dominance

Complete Dominance (Mendel) Review: ◦ Alleles are what code for physical traits ◦ Some alleles are dominant over other alleles (recessive), and therefore suppress their expression ◦ An individual has 3 possible genotypes: homozygous dominant : heterozygous : homozygous recessive ◦ And 2 possible phenotypes: Dominant : Recessive

Examples of Complete Dominance Genotypes �Patterns in F 1 and F 2 generations?

Examples of Complete Dominance �F 3 generation. . . Anything is possible!

Incomplete Dominance �Incomplete dominance is a form of intermediate inheritance in which one allele for a specific trait is not completely dominant over the other allele. �This results in a third phenotype in which the expressed physical trait is a combination of the dominant and recessive phenotypes.

Examples of Incomplete Dominance �Let R= Red �Let W= White �Offspring phenotype are a blend of the two alleles; genotype? �Patterns in F 1 and F 2 generation?

Codominance �A condition in which both alleles of a gene pair in a heterozygote are fully expressed, with neither one being dominant or recessive to the other �Similar to incomplete dominance as it results in three phenotypes and three genotypes

Examples of Codominance b C Let Cb= blue colour Let Cr= red colour Would there be any patterns in the F 1 and F 2 generation? b C Cr C r. C b

Examples of Codominance �Shorthorn Cattle