Answer:
Sometimes during anaphase, chromosomes will fail to separate properly. This is called nondisjunction. Nondisjunction results in cells with abnormal numbers of chromosomes. Instead, one pair of sister chromatids failed to split, resulting in one cell with 5 chromosomes and one cell with 3 chromosomes.
Explanation:
To get ready for mitosis, a cell must first undergo DNA replication during interphase. This process duplicates every strand of DNA so that there are two copies of every chromosome. The two copies are called sister chromatids and are attached at the centromere.
Once DNA replication is complete, nuclear division proceeds in four stages:
Prophase: chromosomes become visible, nuclear envelope disappears, kinetochores and spindle fibers form.
Metaphase: chromosomes align in the center of the cell at the metaphase plate.
<u>Anaphase</u>: chromosomes move outwards, towards opposite poles of the cell.
Telophase: reverse of prophase.
Each sister chromatid of a chromosome has spindle fibers attached to it. These spindle fibers begin to shorten and pull the sister chromatids apart at the centromere. This process of is called disjunction. Now each chromatid is called a daughter chromosome or just a chromosome.
The spindle fibers continue to shorten and move towards opposite ends or poles of the cell. There are also two distinct sets of chromosomes now, and each daughter cell will get one set.
Sometimes during anaphase, chromosomes will fail to separate properly. This is called nondisjunction. Nondisjunction results in cells with abnormal numbers of chromosomes. Instead, one pair of sister chromatids failed to split, resulting in one cell with 5 chromosomes and one cell with 3 chromosomes.
