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Chromosomes & Karyotypes. Chromosomes. 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. Nondisjunction.
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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
Nondisjunction • Chromosomes may fail to separate during meiosis • Resulting gametes may have too few or too many chromosomes
NONDISJUNCTION • Disorders: • Trisomy (an extra chromosome) • DownSyndrome – three 21st chromosomes • Klinefelter’s Syndrome – XXY chromosomes • Edwards Syndrome three 18 chromosomes • Patau’s Syndrome three 13 chromosomes
NONDISJUNCTION Disorders: • Monosomy (one fewer chromosome) • Turner Syndrome – single X chromosome
Normal Male 2n = 46
Normal Female 2n = 46
Male, Trisomy 21 (Down’s) 2n = 47
Female Down’s Syndrome 2n = 47
Klinefelter’s Syndrome 2n = 47
Turner’s Syndrome 2n = 45