Non- Mendelian Genetics

Non-Mendelian Genetics • Exceptions to • Mendel’s Dominance and Recessives

Incomplete Dominance Snapdragon Flowers

Red Snapdragon x White Snapdragon What do you think will happen? Cross- pollinate- If we followed Mendel’s Law one would be dominate over the other

Incomplete Dominance If you cross a red snapdragon (RR) with a white snapdragon (WW) Givens: Red = RR White = WW Pink = RW R R WW  You get all PINK flowers (RW) RW

Incomplete Dominance • Blending in the phenotypes of offspring (where did we see blending?) • Cross two different phenotypes and you get a third phenotype • RR x WW = RW all pink (2 different letters and both capitals) Phenotype Genotype

Incomplete Dominance When F1 generation (all pink flowers) is self –pollinated? Cross_____ x ______ Genotype Phenotype

Incomplete dominance R W R W ___ Red ___ Pink ___ White

Incomplete dominance What happens if you cross a pink with a white? A pink with a red?  

Incomplete Dominance Other Examples: • Hair Texture: Curly hair is incompletely dominant (HH) to straight hair (SS). Those who have wavy hair are intermediate (HS).

Codominance • - both genes contribute to the phenotype • (not blending, both are present) • - Think “Co-captain” – both are equals, together

Codominance • Both genes are Dominant • -Certain types of Chickens have black feathers or white feathers. • -Heterozygous chickens, will have both black and white feathers ( black and white do not blend but appear separately)

Codominance Examples Codominance is seen in animals such as cattle Red=RR, White=WW Roan=RW red and white together Cross_____ x ______

Non- Mendelian Genetics