1. 13.1 Ecologists Study Relationships Unit 3: Genetics Chapter 7 Extending Mendelian Genetics Section 7-1 Chromosomes and Phenotype

2. 7.1 Chromosomes and Phenotype KEY CONCEPT The chromosomes on which genes are located can affect the expression of traits.

3. 7.1 Chromosomes and Phenotype MAIN IDEAS Two copies of each autosomal gene affect phenotype. Males and females can differ in sex-linked traits.

4. 7.1 Chromosomes and Phenotype Objectives Relate dominant-recessive patterns of inheritance in autosomal chromosomes to genetic disorders. Describe patterns of inheritance in sex- linked traits.

5. 7.1 Chromosomes and Phenotype VOCABULARY carrier, carrier, p. 201 sex-linked gene, p. 201 X chromosom inactivation p. 203

6. 7.1 Chromosomes and Phenotype Two copies of each autosomal gene affect phenotype. Mendel studied autosomal gene traits, like hair texture.

7. 7.1 Chromosomes and Phenotype Mendel’s rules of inheritance apply to autosomal genetic disorders. –A heterozygote for a recessive disorder is a carrier. –Disorders caused by dominant alleles are uncommon. (dominant)

8. 7.1 Chromosomes and Phenotype Males and females can differ in sex-linked traits. Genes on sex chromosomes are called sex-linked genes. –Y chromosome genes in mammals are responsible for male characteristics. –X chromosome genes in mammals affect many traits.

9. 7.1 Chromosomes and Phenotype Male mammals have an XY genotype. –All of a male’s sex- linked genes are expressed. –Males have no second copies of sex-linked genes.

10. 7.1 Chromosomes and Phenotype MAIN IDEAS Two copies of each autosomal gene affect phenotype. Males and females can differ in sex-linked traits. VOCABULARY carrier, carrier, p. 201 sex-linked gene, sex-linked gene, p. 201 X chromosome X chromosome inactivation p. 203 MAIN IDEA Two copies of each autosomal gene affect phenotype. Objectives Relate dominant-recessive patterns of inheritance in autosomal chromosomes to genetic disorders. Describe patterns of inheritance in sex-linked traits.

11. 7.1 Chromosomes and Phenotype Female mammals have an XX genotype. –Expression of sex-linked genes is similar to autosomal genes in females. –X chromosome inactivation randomly “turns off” one X chromosome.