1. Karyotype And Pedigrees

2. What is a Karyotype Chromosome preparation of an individual
They are organized as
Homologous chromosomes are paired by identical centromere position, identical staining pattern and size
Arranged by size
The sex chromosomes are at the end

3. Human Karyotype

4. Karyotype Preparation
Cultured cells are arrested at metaphase by adding colchicine
This is when chromosomes are most condensed and easiest to identify

5. Karyotype Preparation
Arrested cells are broken open
Metaphase chromosomes are fixed and stained
Chromosomes are photographed through microscope
Photograph of chromosomes is cut up and arranged to form Karyotype diagram

6. Human Karyotype

7. Uses of Karyotyping Ascertain sex
Identify chromosomal abnormalities Ex. Down’s syndrome,
Identify abnormal chromosomes Ex. Breakages and nonreciprocal crossing over

8. Pedigree Chart that shows genetic connections among individuals
Uses Standardized symbols
Able to use knowledge of probability and Mendelian patterns used to suggest basis of a trait
Conclusions most accurate when drawn from large number of pedigrees

9. Fig. 11-7a, p.172

10. A Pedigree problem Is this trait dominant or recessive?
Is this trait sex linked or autosomal?
What does the half shaded symbols mean?
What is the genotype of individual A A

11. Pedigree for Polydactyly
Fig. 11-7b, p.172

12. Why Pedigree Studies? To understand human inheritance patterns
To understand how traits are inherited without using test crosses
To be able to predict inheritance pattern for prospective parents

13. Pedigree of Huntington’s Disease
Fig. 11-8, p.173

14. Pedigree of European Royal Family and Hemophilia
Fig a, p.175