Monosomy

Monosomy

• Definition: Each cell lacks one chromosome from a pair, designated as $2n-1$.
• Cause: Nondisjunction of homologous chromosomes (Anaphase I) or sister chromatids (Anaphase II), producing an abnormal gamete ($n-1$).
• Result: Fertilization of an $n-1$ gamete with a normal $n$ gamete leads to a $2n-1$ zygote.
• Human Impact: Results in 45 chromosomes in humans.
• Examples:
  • Autosomal: Monosomy 21
  • Sex Chromosome: Turner Syndrome