VARIATIONS TO SIMPLE DOMINANCE

Its not always as straight forward as it seems…

THE PROBLEM…

• A red carnation is crossed with a white carnation. The resulting flowers are all pink.

• What is up with that?

Incomplete Dominance

– Neither allele dominates the other

– Phenotype is intermediate

– Red flower + White flower = pink flower

– Tall plant + Short plant = medium plant

THE SYMBOLISM ISSUE

• Red is not dominant• White is not recessive• We can no longer use capital and lower case

letter as symbolism

THE SYMBOLISM ISSUE

• We use a base letter – C for “color”

• And a superscript to indicate which one.

INCOMPLETE DOMINANCETHE MONOHYBRID CROSS

CROSS TWO F1 OFFSPRING

CROSS TWO PINK FLOWERS

THE PUNNET SQUARE

CODOMINANCE

– CO MEANS SHARED OR DONE TOGETHER

– Is similar to Incomplete dominance– BUT Instead of blending, – both traits show up!

WADDING ROCKS!!!!

I am a squirl

Do Humans taste like chicken ?

CODOMINANCE– BOTH TRAITS SHOW UP!!!– Black chicken + White chicken = chicken with

both black feathers and white feathers

CODOMINANCE– BOTH TRAITS SHOW UP!!!– BROWN horse and a WHITE horse produce

a roan horse – both BROWN hairs and WHITE hairs…