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Chromosomes 2

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 3

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 4

Normal Male 5 2n = 46

Normal Female 6 2n = 46

Male, Trisomy 21 (Down’s) 7 2n = 47

Female Down’s Syndrome 8 2n = 47

Klinefelter’s Syndrome 9 2n = 47

Turner’s Syndrome 10 2n = 45

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