Question

Triple X syndrome, or trisomy X, occurs when a female has an extra X chromosome in each of her cells. This results when the mother's reproductive cells divide improperly, and two X chromosome are moved into one gamete. When that gamete is fertilized and the father's DNA and X chromosome are combined with the mother's, that gives the cell three X chromosomes instead of two. Triple X syndrome occurs because of _______.

Answer 1

nondisjunction

Step-by-step explanation:

Answer 2

The answer is nondisjunction.

Nondisjunction is the failure of homologous chromosomes to separate during cell division. Therefore, if the mother's reproductive cells divide improperly and two X chromosomes fail to separate, both X chromosomes from the mother will move into one gamete. Together with another X chromosome from the father, the cell will have three X chromosomes instead of two.