Karyotypes Chromosomal Abnormalities Karyotyping A Karyotype is a

Karyotypes & Chromosomal Abnormalities

Karyotyping • A Karyotype is a picture of real chromosomes arranged in homologous pairs • Scientists or doctors take photos of a cell during division and “unscramble” the chromosomes using computer software

Two Types of Chromosomes Sex Chromosomes • Determine the sex of the organism • Typical human male: X Y • Typical human female: X X • 1 pair in humans Autosomes • All other chromosomes • 22 pairs in humans

Typical Human Karyotypes Male Female

Chromosomal Disorders In nondisjunction chromosomes do not separate properly during meiosis; changes the final number of chromosomes • Trisomy – 3 copies of a chromosome (1 extra) • Monosomy – 1 copy of a chromosome (1 less)

Chromosomal Disorders

Chromosomal Disorders Male or Typical female? or What kind of atypical? abnormality has occurred? Trisomy 21 (Down Syndrome)

Chromosomal Structural Disorders mutations affect chunks of chromosomes but do not change the Often difficu lt o r impo total chromosome number ssib • • le to see o chromosome karyot n a ype! Deletion – loss of a chunk of Duplication – many extra copies of chunk Inversion – direction of chunk reversed Translocation – chunk breaks off and relocates to a NON-homologous chromosome