Terminology

Homozygote
AA or aa
Heterozygote
Aa

n indicates the number of genome copies.

Cohesins
Keep sister chromatids together.
Ploidy
The number of complete sets of chromosomes in a cell.
Aneuploidy
An abnormal number of sets of chromosomes.
  • Due to mitotic nondisjunction (spindle fiber/anaphase error).
  • Trisomy, Monosomy, Nullisomy, Tetrasomy.