4. Nondisjunction and Karyotypes

what is Nondisjunction

Nondisjunction: the failure of homologous chromosomes to separate during cell division

Monosomy and Trisomy

• Monosomy is when there’s only one copy of a chromosome

• trisomy is when there are three copies of a chromosome

Nondisjunction during mitosis

the cell either kills itself or the immune system kills it so its not a big deal

Cytogenetic testing

testing to see if baby is affected by nondisjunction

Amniocentesis and Chorionic villus sampling

These are both common methods of cytogenetic testing

• Amniocentesis: extract sample of the amniotic fluid containing fetal cells

• Chorionic villus sampling: extract sample of placental cells

Visualizing chromosomes

the act of artificially staining chromosomes so they become visible and identifiable.

Karyotyping and Karyograms

• karyotype: complete visualized set of an organisms chromosomes

• karyogram: homologous chromosomes side by side

What is down syndrome

down syndrome is when there is an extra copy of chromosome 21 (trisomy 21)