How do the stages of mitosis and meiosis occur in a specific order and never alternate.

The cell divides by the two main process known as mitosis and meiosis. The somatic cells divide by the process of mitosis and germ cells divide by the process of meiosis.

The cell follows the sequential pathway - prophase, metaphase, anaphase and telophase. This specific order follows because the cell cycle have various check point at each stage of the cell cycle. The cyclins and cdk's regulate the transitions from one stage to another stage of the cell cycle. If the cell correctly passes these transition without any defects in the cell.

cell division is not regulated in tumor cells.