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





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



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!