NEET 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: -In anaphase, sister chromatids (now called chromosomes) are pulled toward opposite poles. In telophase, chromosomes arrive at opposite poles, and nuclear envelope material surrounds each set of chromosomes.