To prepare for division, cells must go through interphase, which is divided into three stages. Finally, in G2, the second gap phase, cells continue to grow, multiply organelles and proteins that are required for mitosis, and replenish their energy stores. The cell is now ready to enter the first stage of mitosis.

The Mitosis Cell Cycle Interphase is the period when a cell is getting ready to divide and start the cell cycle. During this time, cells are gathering nutrients and energy. The parent cell is also making a copy of its DNA to share equally between the two daughter cells.

Before mitosis begins, the chromosomes in the nucleus of the cell undergo replication. This is because mitosis produces two daughter cells identical to the parent cell; so the number of chromosomes in the parent and daughter cells must be the same. Mitosis produces two diploid cells from one diploid cell.

Once mitosis is complete, the cell has two groups of 46 chromosomes, each enclosed with their own nuclear membrane. The cell then splits in two by a process called cytokinesis, creating two clones of the original cell, each with 46 monovalent chromosomes.

The main events of prophase are: the condensation of chromosomes, the movement of the centrosomes, the formation of the mitotic spindle, and the beginning of nucleoli break down.

During prophase I, the homologous chromosomes condense and become visible as the x shape we know, pair up to form a tetrad, and exchange genetic material by crossing over. In telophase I, chromosomes move to opposite poles; during cytokinesis the cell separates into two haploid cells.

During prophase, the replicated pairs of chromosomes condense and compact themselves. The pairs of chromosomes that have been replicated are called sister chromatids, and they remain joined at a central point called the centromere.