1. Genetics Pedigrees and Karyotypes

2. Karyotype

3. Karyotype What to look for in a karyotype?
When analyzing a human karyotype, scientists first look for these main features:
Are there 46 chromosomes?
Are there 2 identical pairs of each autosome and 2 sex chromosomes?
Are there any rearrangements between chromosomes or large deletions?

4. Chromosomes Humans have 46 chromosomes 44 chromosomes are autosomes
2 are sex chromosome
Females have two X chromosomes
Males have one X and one small Y chromosome

5. Pedigrees
FEMALE
MALE
Half shaded means the person is not “affect”, but is a carrier of the disorder
Shaded means the person is “affect” by a disorder
Unshaded means the person is not “affect”

6. Pedigrees
MARRIED
THE SON & HIS WIFE
THEIR KIDS
THEIR KIDS

7. Inheritance of sex chromosomes
Egg cells contain one X chromosome
Sperm cells contain either one X chromosome or one Y chromosome
So in a human population, half are male and half are female

8. Sex linked Genes
Genes located on the sex chromosomes are called sex-linked genes.
Males have just one X chromosome, so all X-linked alleles are expressed in Males

9. Sex-Linked Genes What percent of offspring will be girls?
What percent of offspring will be boys?
What percent of offspring will have normal vision?
What percent of offspring will be colorblind?
What percent of offspring will be carriers?

10. Hemophilia Pedigree

11. Chromosomal Disorders
Nondisjunction

12. Chromosomal Disorders
Down syndrome
Trisomy 21
Due to non-disjunction in second stage of meiosis

13. Chromosomal Disorders
Turner’s Syndrome
What is missing?
Karyotype is (45,X)
Only one X chromosome

14. Chromosomal Disorders
Klinefelter’s Syndrome
What is extra?
Karyotype 47 XXY
Extra X chromosome