Achondroplasia

Karyotypes and Nondisjunction

KaryotypePicture of a persons’ chromosomes

Allows doctors to detect some genetic disorders

Reveals extra or missing chromosomes

KaryotypesPicture taken during metaphase of mitosis

Chromosomes are condensed and consist of 2 sister chromatids

DNA is stained prior to taking the picture. Similar DNA sequences glow similarly

Arranged by decreasing size

Telomeres

The ends of a chromosome

They serve a protective function

Their degradation leads to aging and cancer

Nondisjunction

Nondisjunction

Occurs when Sister Chromatids fail to separate

Can happen in Meiosis I or Meiosis II

Wrong number of chromosomes in a gamete

Nondisjunction

Down syndrome occurs because of an extra chromosome 21

Down syndrome

Occurs because of nondisjunction

Also called trisomy 21

Nondisjunction

Monosomy

Only 1 of a particular chromosome

Nondisjunciton and Sex Chromosomes