Genetics Codominance Incomplete Dominance Warm up What happens

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Genetics Codominance & Incomplete Dominance

Genetics Codominance & Incomplete Dominance

Warm up • What happens if you mix yellow paint with blue paint? •

Warm up • What happens if you mix yellow paint with blue paint? • How could this be used as an analogy to describe the inheritance of certain traits?

Exceptions in Inheritance of Traits • Not all traits are inherited as dominant or

Exceptions in Inheritance of Traits • Not all traits are inherited as dominant or recessive from a single gene (pair of alleles). – Incomplete dominance – Codominance – One gene, many traits – Many genes, one trait – Environmental impact

One Gene, Many Traits • Sometimes, one gene influences more than one trait. –

One Gene, Many Traits • Sometimes, one gene influences more than one trait. – Ex: white tiger • Gene for white fur also causes blue eyes

Many Genes, One Trait • Some traits are the result of several genes acting

Many Genes, One Trait • Some traits are the result of several genes acting together. – Ex: color of your skin, hair, and eyes • Difficult to tell if the traits are a result of a dominant or recessive allele. At least two genes determine human eye color. That’s why many shades of a single color are possible.

The Importance of Environment • A dog with the genes for long fur could

The Importance of Environment • A dog with the genes for long fur could have its fur cut short. • You may have the genotype to grow tall, but you need a healthy diet to reach your full height.

Foldable Codominance Incomplete Dominance

Foldable Codominance Incomplete Dominance

Codominance Red x White = Red & White • Co = together – coexist

Codominance Red x White = Red & White • Co = together – coexist (exist together) – cooperate (work together) • In codominance, both traits appear (both traits are equally dominant)

Punnett Square Example CR CW CW CR CR CW C = color CRCR =

Punnett Square Example CR CW CW CR CR CW C = color CRCR = red CWCW = white CRCW = red & white 1. Parents with two different phenotypes produce offspring with a third phenotype. 2. Both parents’ traits show up together in the offspring.

Another Example of Codominance

Another Example of Codominance

Other Codominance Examples • Cattle – Red x White = Roan • Human Blood

Other Codominance Examples • Cattle – Red x White = Roan • Human Blood Types – A x B = AB

Incomplete Dominance • Incomplete dominance – produces a mixing or blend of the two

Incomplete Dominance • Incomplete dominance – produces a mixing or blend of the two traits • Red x White = Pink

Punnett Square Example R R W RW RW RR = red WW = white

Punnett Square Example R R W RW RW RR = red WW = white RW = pink 1. Parents with two different phenotypes produce offspring with a third phenotype. 2. Both parents’ traits show up together in the offspring.

Another Example of Incomplete Dominance • Horses – Chestnut brown x creamy white =

Another Example of Incomplete Dominance • Horses – Chestnut brown x creamy white = palomino

Practice: Codominance & Incomplete Dominance • Incomplete and Codominant practice worksheet. doc

Practice: Codominance & Incomplete Dominance • Incomplete and Codominant practice worksheet. doc