1. Genetics Conception: ovum and sperm fuse to create zygote Chromosomes: contain all biologically inherited information (DNA) Ovum: 23 chromosomes (mom’s contribution) Sperm: 23 chromosomes (dad’s contribution)

2. Zygote 46 chromosomes (23 pairs: 23 from mom and 23 from dad) 22 pairs are called autosomes 23rd pair contain the sex chromosomes

4. Karotype

5. Mitosis Cell division resulting in new diploid cells (46 chromosomes) Chromosomes replicate, then split into two diploid cells

6. Mitosis Body Cell 46Chromosomes Daughter Cell 46Chromosomes 46Chromosomes

7. Meiosis Cell division resulting in haploid (23 chromosomes) cells Creation of gametes (sex cells: ovum and sperm)

8. Meiosis Germ Cell 46Chromosomes Gamete23ChromosomesGamete23Chromosomes

9. Polygenic Inheritance Affected by many genes rather than by a single pair.

10. Sex-linked Chromosomal Abnormalities Kleinfelter’s syndrome: XXY XYY syndrome Fragile X XXX Turner’s syndrome

11. Non Sex-linked Chromosomal Abnormalities Down Syndrome (Trisomy 21) –Translocation trisomy –Mosaicism –Nondisjunction during meiosis

12. Down Syndrome

13. Simian Crease

14. Maternal Age – Chromosomal Abnormalities AgeTrisomy 21 rateOther chromosomal rate 201/16671/526 251/12501/476 301/9521/385 351/3781/192 401/1061/66 451/301/21

15. Genetic Disorders TaySachs (autosomal recessive) Cystic Fibrosis (autosomal recessive) Phenylketonuria (PKU) (recessive) Muscular Dystrophy (dominant)