1. 1copyright cmassengale

2. Chromosomes 2

3. Chromosome Number All cells in the human body (SOMATIC CELLS) have 46 or 23 pairs of chromosomes Called the DIPLOID or 2n number GAMETES (eggs & sperm) have only 23 chromosomes Called the MONOPLOID or 1n number 3copyright cmassengale

4. Nondisjunction Chromosomes may fail to separate during meiosis Resulting gametes may have too few or too many chromosomes Disorders: Down Syndrome – three 21 st chromosomes Turner Syndrome – single X chromosome Klinefelter’s Syndrome – XXY chromosomes 4copyright cmassengale

5. Normal Male 5 2n = 46 copyright cmassengale

6. Normal Female 6 2n = 46 copyright cmassengale

7. Male, Trisomy 21 (Down’s) 7 2n = 47 copyright cmassengale

8. Female Down’s Syndrome 8 2n = 47 copyright cmassengale

9. Klinefelter’s Syndrome 9 2n = 47 copyright cmassengale

10. Turner’s Syndrome 10 2n = 45 copyright cmassengale

11. 11copyright cmassengale