1. Chapter Seven: Extending Mendelian Genetics

2. Section One: Chromosome and Phenotype
Different alleles produce different phenotypes
Genetic disorders can be predicted by examining alleles
Disorders can be caused by recessive alleles
Caused by recessive alleles on autosomes
2 copies of the recessive allele must be present to cause the disorder
Carrier: does not show symptoms of the disease, but can cause the disease causing allele to offspring
Disorders can be caused by dominant alleles
Less common

3. Section One: Chromosomes and Phenotype
Sex-linked Traits
Sex-linked genes: genes located on the sex chromosomes
X chromosomes have more influence over phenotype
Males only get one copy of X and one copy of Y
Which means if the copy a male receives is recessive, it will be expressed
X Chromosome Inactivation: in females, one of the two x chromosomes is “inactivated”

4. Section Two: Complex Patterns of Inheritance
Incomplete and Codominance
Incomplete Dominance: a heterozygous phenotype is somewhere between the 2 homozygous phenotypes
Codominance: both traits are fully and separately expressed

5. Section Two: Complex Patterns of Inheritance
Polygenic Traits and Epistasis
Polygenic Trait: traits produced by two or more genes
Example: Human skin color and eye color
Epistasis: one gene interferes with the expression of other genes
Example: albinism

6. Section Two: Patterns of Inheritance
Environment and Genotype
Temperature dependent sex determination
Are the nutrients necessary for that trait present?

7. Section Three: Gene Linkage and Mapping
Linkage Maps
Maps of relative locations, or loci, of genes on a chromosome
Shows how often crossing over occurs between two genes occur
The farther apart two genes are on the genome, the more likely they are to cross over

8. Section Four: Human Genetics and Pedigrees
Females carry sex-linked genetic disorders
They are called carriers
They have an extra X chromosome to override the X chromosome with the disorder
When males receive the X chromosome with the disorder, they do not have another X chromosome, only a Y chromosome

9. Section Four: Human Genetics and Pedigrees
Pedigree: a chart that can help trace the phenotypes and genotypes in a family to determine whether people carry recessive alleles
Can be used for autosomal genes and sex-linked genes

10. Section Four: Human Genetics and Pedigrees
Tracing Autosomal Genes

11. Section Four: Human Genetics and Pedigrees
Tracing Sex-linked Genes

12. Section Four: Human Genetics and Pedigrees
Mapping Human Chromosomes
Karyotype: a picture of all the chromosomes in a cell
Can show changes in chromosomes
Deletions or extra copies