What is at is nondisjunction What gametes will form if nondi

What is at is non-disjunction? What gametes will form if non-disjunction of the sex chromosomes oc in the following: Division Resulting Gametes (include normal and abnormal ones) Meiosis l in the female Meiosis ll in the female Meiosis I in the male Meiosis II in the male Table 3 What egg and sperm combinations can give rise to the following sex chromosome abnormalities in the chil- dren? Triple-x syndrome (xxx) Klinefelter\'s syndrome (XXY) Turner\'s syndrome (XO) Jacob\'s syndrome CXYY)

Solution

Answer:

Nondisjunction means that a chromosome pair failed to separate during the meiotic division. This will create one daughter cell with an extra chromosome and another daughter cell with one too few chromosomes.

Gametes formed when non disjunction takes place in:

a. Meiosis I in the female: XX and O.

b. Meiosis II in the female: XX, O and X (non disjunction in one of the cells, the other undergoes normal disjunction)

XX and O (when non disjunction occurs in both cells after meiosis I)

c. Meiosis I in male: XY and O.

d. Meiosis II in male: (3 conditions may occur)

i. When non disjunction takes place in both cells after meiosis I: XX, YY and O

ii. When non disjunction takes place only in the cell containing X after meiosis I: XX, O and Y

iii. When non disjunction takes place only in the cell containing Y after meiosis I: YY, X and O.