NEET BIOLOGY

Detailed explanation-1: -At the beginning of nuclear division, two wheel-shaped protein structures called centrioles position themselves at opposite ends of the cell forming cell poles. Long protein fibers called microtubules extend from the centrioles in all possible directions, forming what is called a spindle.

Detailed explanation-2: -And when the chromosomes are condensing to undergo mitosis, the centrioles form the areas that mitotic spindle forms from. And those mitotic spindles go and attach to each of the chromosomes and pull the chromosomes to opposite ends of the cell to allow cytokinesis, then, to occur.

Detailed explanation-3: -The structure involved in the formation of spindle fibres are centrioles. They exist in a pair close to the nucleus and are present only in the animal cell.

Detailed explanation-4: -Answer and Explanation: Spindle fibers are created by small organelles called centrosomes during the second phase (prophase) of mitosis and meiosis. Spindle fibers are made up of many microtubules which are long strands of protein located on the sides of cells.

Detailed explanation-5: -Centrioles are responsible for organizing the spindle fibers in the mitotic spindle apparatus and are thought to participate in the completion of cytokinesis during the process of cell division.