AP BIOLOGY

Detailed explanation-1: -Prophase. The first and longest phase of mitosis is prophase. During prophase, chromatin condenses into chromosomes, and the nuclear envelope, or membrane, breaks down . In animal cells, thecentrioles near the nucleus begin to separate and move to opposite poles (sides) of the cell.

Detailed explanation-2: -At the beginning of the first mitotic stage, prophase, the thread-like doubled chromosomes contract and become visible. The two centrioles move to opposite sides of the nucleus.

Detailed explanation-3: -Centrioles begin moving to opposite ends of the cell and fibers extend from the centromeres. Some fibers cross the cell to form the mitotic spindle. The nuclear membrane dissolves, marking the beginning of prometaphase. Proteins attach to the centromeres creating the kinetochores.

Detailed explanation-4: -Anaphase. The sister chromatids separate from one another and are pulled towards opposite poles of the cell. The microtubules that are not attached to chromosomes push the two poles of the spindle apart, while the kinetochore microtubules pull the chromosomes towards the poles.

Detailed explanation-5: -During prophase, the centrioles move to opposite ends of the nucleus and a mitotic spindle of threads begins to appear. Those threads then connect to the now apparent chromosomes. During anaphase, the chromosomes are split and pulled towards each centriole.