1-Aneuploid gametes are cells that contain the wrong number of chromosomes. Aneu
ID: 8923 • Letter: 1
Question
1-Aneuploid gametes are cells that contain the wrong number of chromosomes. Aneuploidy occurs as a result of nondisjunctions. At what point in meiotic cell division would nondisjunction occur?
2-The DNA content of a diploid cell in the G1 phase of the cell cycle is measured. If this DNA content is X, then the DNA content of the same cell at metaphase I would be
a. 0.25X
b. 0.5X
c. X
d. 2X
e. 4X
3- If we continued to follow the cell lineage from question 1, then the DNA content at metaphase of meiosis II would be
a. 0.25X
b. 0.5X
c. X
d. 2X
e. 4X
Explanation / Answer
1. Nondisjunction occurs in the following points in meiotic cell division: Weakened or completely inactive mitotic checkpoints When one kinetochore is attached to both mitotic spindle poles formation of more than 2 spindle poles formation of only a single spindle pole --------------------------------------------------------------- 2.The answer is D. In G1 phase, the cells are preparing for division. In prophase the DNA replicates. Hence in metaphase the DNA content would be 2X. ------------------------------------------------------------- 3. The answer is B. Meiosis is a reduction division. The cell coming out of mitosis would have 2n number[X]. In meiosis reduction occurs. Hence during metaphase II of meiosis, the genetic material would be 0.5X.
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