NEET BIOLOGY

Detailed explanation-1: -Early prophase. The mitotic spindle starts to form, the chromosomes start to condense, and the nucleolus disappears. In early prophase, the cell starts to break down some structures and build others up, setting the stage for division of the chromosomes.

Detailed explanation-2: -During prophase, chromatin condenses into chromosomes, and the nuclear envelope (the membrane surrounding the nucleus) breaks down. In animal cells, the centrioles near the nucleus begin to separate and move to opposite poles of the cell.

Detailed explanation-3: -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. As the centrioles move, a spindle starts to form between them.

Detailed explanation-4: -During metaphase, the nuclear membrane disappears and the chromosomes become aligned half way between the centrioles. The centromere of each doubled chromosome becomes attached by thread-like spindle fibers to the centrioles which are at polar opposite sides of the cell.