1. Other Patterns of Inheritance

2. Think About It! What is a pattern? Give an example. What is inheritance?

3. Cross Types A cross represents the transfer of genetic material from one organism to another. This an be illustrated by a Punnett square This an be illustrated by a Punnett square The square is used to predict the results of a cross. Is named for the British geneticist Reginald Punnett. Show all the possible gamete combinations.

4. Cross Types Monohybrid crosses Focuses on only one trait. The Punnett square for this type of cross has four boxes.

5. Cross Types The ratio of a homozygous monohybrid cross is 100% KEY: B- black coat b- brown coat BB bBbBb bBbBb

6. Cross Types The ratio of a heterozygous monohybrid cross is 3:1. KEY: B- black coat b- brown coat Bb BBBBb bBbbb

7. Cross Types Dihybrid crosses Focus on two traits. Focus on two traits. The Punnett square for this type of cross has sixteen boxes. The Punnett square for this type of cross has sixteen boxes. The ratio of a heterozygous dihybrid cross is 9:3:3:1. The ratio of a heterozygous dihybrid cross is 9:3:3:1.

8. Other Patterns of Inheritance Many genes do not follow Mendel’s patterns of inheritance. Factors that can influence heredity include Incomplete dominance Incomplete dominance Co-dominance Co-dominance Multiple Alleles Multiple Alleles Polygenic traits Polygenic traits Environmental conditions Environmental conditions

9. Incomplete Dominance The offspring exhibits a trait that is an intermediate form of the parent’s traits. The phenotype is a blend of the two homozygous phenotypes.

10. Co dominance Two traits in a heterozygote are fully expressed.

11. Co dominance

12. Multiple Alleles Some traits are controlled by genes that have two or more alleles. Multiple allele traits are hair and eye color.

13. Polygenic Traits Are traits that are controlled by more than one pair of genes. Examples include height, weight, and skin color.

14. Polygenic Traits

15. Environmental conditions An individual’s phenotype often depends on the surrounding environment. Examples: arctic fox and hare