1. CHAPTER 12: GENETICS

2. Lesson 2: UNDERSTANDING INHERITANCE

3. ?? Essential Questions What determines the expression of traits?
How can inheritance be modeled?
How do some patterns of inheritance differ from Mendel’s model?

4. Vocabulary Gene Punnet square Allele Imcomplete dominance Phenotype
Codominance
Genotype
Polygenic inheritance
Homozygous
Heterozygous

5. What controls traits? Chromosomes Genes and Alleles
A gene is a section on a chromosome that has genetic information for the trait
The different forms of a gene are called alleles

6. What controls traits? Genotype and Phenotype
Geneticists call how a trait appears, or is expressed, the trait’s phenotype
The two alleles that control the phenotype of a trait are called the trait’s genotype
When the two alleles of a gene are the same, its genotype is homozygous
If the two alleles of a gene are different, its genotype is heterozygous

7. Modeling Inheritance Punnett Squares Analyzing a Punnet Square
A Punnet square is a model used to predict possible genotypes and phenotypes of offsprings
Analyzing a Punnet Square

8. Modeling Inheritance
Using Ratios to Predict
Pedigrees

9. Complex Patterns of Inheritance
Types of Dominance
Incomplete Dominance: alleles show incomplete dominance when the offspring’s phenotype is a combination of the parents’ phenotypes
Codominance: When both alleles can be observer in a phenotype, this type of interaction is called codominance

10. Complex Patterns of Inheritance
Multiple Alleles
Some genes have more than two alleles, or multiples alleles, like human ABO type.
Sex-Linked Traits
Females have two X chromosomes, males have an X and a Y chromosome
Polygenic Inheritance
Polygenic Inheritance occurs when multiple genes determine the phenotype of a trait

11. Genes and the Environment
An organism’s genotype determines its phenotype.
Scientist have learned that genes are not the only factors that can affect its phenotype
An organism’s environment can also affects its phenotype

12. Classwork
Page 435 #1, 2, 3, 4, 5, 6, 7, and 8 Write down questions and answers Workbook page