1. There are many variations of inheritance patterns Ch. 10.3

2. Mendel used very simple pea plant characteristics to study genetics Mendel used very simple pea plant characteristics to study genetics Unfortunately, not all characteristics are that easy to ‘see.’ Unfortunately, not all characteristics are that easy to ‘see.’

3. Intermediate Inheritance In Mendel’s pea crosses, the F 1 generation looked like the dominant homozygous parent. In Mendel’s pea crosses, the F 1 generation looked like the dominant homozygous parent. In the F 2 generation, there was also homozygous recessive being expressed In the F 2 generation, there was also homozygous recessive being expressed However, in some organisms, dominant and recessive are not easily expressed However, in some organisms, dominant and recessive are not easily expressed

4. Neither allele is dominant and the phenotype is INTERMEDIATE between the phenotype of the homozygous dominant and recessive trait Neither allele is dominant and the phenotype is INTERMEDIATE between the phenotype of the homozygous dominant and recessive trait INTERMEDIATE INHERITANCE INTERMEDIATE INHERITANCE

6. Do NOT use a capital letter and a lowercase letter because NEITHER allele is dominant Do NOT use a capital letter and a lowercase letter because NEITHER allele is dominant

7. Multiple Alleles Many genes have several alleles that exist in the population (making the # of phenotypes and genotypes larger) Many genes have several alleles that exist in the population (making the # of phenotypes and genotypes larger) Multiple alleles with human blood type Multiple alleles with human blood type A, B, AB, O A, B, AB, O

9. CODOMINANCE  heterozygous for both traits CODOMINANCE  heterozygous for both traits DIFFERENT from intermediate inheritance DIFFERENT from intermediate inheritance The individual’s phenotype is not intermediate, but rather shows the SEPARATE traits of both alleles The individual’s phenotype is not intermediate, but rather shows the SEPARATE traits of both alleles

10. Polygenic Inheritance Sometimes, multiple GENES affect a single character (POLYGENIC INHERITANCE) Sometimes, multiple GENES affect a single character (POLYGENIC INHERITANCE) Height, eye color, skin color, etc Height, eye color, skin color, etc

11. The Importance of Environment Just because there is a certain GENOTYPE for an organism, that does not mean the environment doesn’t play a role Just because there is a certain GENOTYPE for an organism, that does not mean the environment doesn’t play a role i.e. trees having different leaf color/size/greenness from year to year i.e. trees having different leaf color/size/greenness from year to year nutrition in humans, exercise, sunlight, etc. nutrition in humans, exercise, sunlight, etc.

12. Concept Check For a trait with intermediate inheritance, what is the phenotypic ratio for F2 offspring of a monohybrid cross? How is that different from a simple dominant- recessive cross? For a trait with intermediate inheritance, what is the phenotypic ratio for F2 offspring of a monohybrid cross? How is that different from a simple dominant- recessive cross? Two parents have type O blood. What blood type would you expect for their first child? Two parents have type O blood. What blood type would you expect for their first child? What is the likely mechanism of inheritance for a character with a large range of phenotypes? Explain. What is the likely mechanism of inheritance for a character with a large range of phenotypes? Explain. Give three examples of human physical characters affected by environment. Give three examples of human physical characters affected by environment.