Meiosis Mistakes Human chromosome abnormalities Nondisjunction Failure of homologous chromosomes to separate during cell division Results 1 too many OR 1 too few chromosomes Trisomy: one too many 47 chromosomes Monosomy: one too few 45 chromosomes How can we diagnose these abnormalities? Karyotypes Picture of chromosomes in a dividing (div.) cell Arranged in order by size Why might this be useful? Prenatal testing amniocentesis Down’s syndrome Short stature Round face Developmental Delays Eyelids that Cover inner corner Of eyes Trisomy-21 Klinefelter’s syndrome Affects only males Sterile Varying affects Extra X Chromosome Edward’s syndrome Growth deficiency Feeding difficulties Breathing difficulties Developmental delays Underdevelopped organs Small head Low-set, malformed ears Cleft lip/palate Overlapped, flexed fingers Trisomy 18 Patau syndrome heart defects sloping forehead, small or missing eyes, low set ears, cleft palate extra fingers and toes Developmental delays Trisomy-13 Who determines the sex of the child? THE FATHER!