AP BIOLOGY

Detailed explanation-1: -Aneuploidy. A genetic condition where someone has either too many or two few chromosomes is called aneuploidy (AN-yoo-ploy-dee). A complete set of genetic information includes 23 pairs of chromosomes, which adds up to 46 chromosomes total. This number includes 22 pairs of autosomes, and one pair of sex chromosomes.

Detailed explanation-2: -Classical disorders of sex chromosome are Klinefelter syndrome, XX male, XYY male, Turner syndrome, XXX female, and XY female. True hermphroiditism, mixed gonadal dysgenesis, and pure gonadal dysgenesis are also included, because most of these disorders have abnormal sex chromosome.

Detailed explanation-3: -Theoretically, non-disjunction may occur in both the male and female germ cells at either the first or second meiotic division and may give rise to a considerable variety of non-disjunctional types in the progeny.

Detailed explanation-4: -Nondisjunction occurs when chromosomes fail to segregate during meiosis; when this happens, gametes with an abnormal number of chromosomes are produced. The clinical significance is high: nondisjunction is the leading cause of pregnancy loss and birth defects.