7 2 Complex Patterns of Inheritance Complex patterns

7. 2 Complex Patterns of Inheritance Complex patterns of inheritance

7. 2 Complex Patterns of Inheritance Phenotype can depend on interactions of alleles. • In incomplete dominance, neither allele is completely dominant nor completely recessive. – Heterozygous phenotype is intermediate between the two homozygous phenotypes • Heterozygous is like a “blend”

7. 2 Complex Patterns of Inheritance Example: Cross a homozygous red carnation flower (RR) with a homozygous white flower (WW). • List the genotypes. 4 RW • List the phenotypes. 4 Pink

7. 2 Complex Patterns of Inheritance Example: Cross one heterozygous pink (RW) 4 o’clock flower with a White flower (WW). • List the genotypes. 2 RW, 2 WW • List the phenotypes. 2 Pink, 2 White

Codominan • Defined: When both alleles are ce dominant and equally 7. 2 Complex Patterns of Inheritance expressed • The colors do NOT blend together, but are equally seen • Ex: Cattle Coat Red cow x White cow = Roan Cow • Ex: Human Blood types Type A x Type B = Type AB

7. 2 Complex Patterns of Inheritance • Blood types are another example of codominance. – The ABO blood types result from codominant alleles – This blood group consists of 3 different alleles • Dominant A allele • Dominant B allele • Recessive O allele • A and B are equally dominant • Many genes have more than two alleles.

7. 2 Complex Patterns of Inheritance Ex: Cross Jason who is homozygous for type A blood with Maria who is homozygous for type B blood. • List the genotypes. 4 AB • List the phenotypes. 4 type AB blood

7. 2 Complex Patterns of Inheritance Ex: Cross Mike who is heterozygous for type A blood with Lisa who is heterozygous for type B blood. • List the genotypes. 1 AB, 1 Ao, 1 Bo, 1 oo • List the phenotypes. 1 type AB blood 1 type A blood 1 type B blood 1 type o blood • Probability of Heterozygous individual? 75%

7. 2 Complex Patterns of Inheritance Many genes may interact to produce one trait. • Polygenic traits are produced by two or more genes. Order of dominance: brown > green > blue.

7. 2 Complex Patterns of Inheritance • An epistatic gene can interfere with other genes. • This is like a “knock out” gene

7. 2 Complex Patterns of Inheritance The environment interacts with genotype. • Phenotype is a combination of genotype and environment. • The sex of sea turtles depends on both genes and the environment • Height is an example of a phenotype strongly affected by the environment.