The genetic information of the cell, or DNA, is stored in the nucleus. During mitosis, two nuclei must form, so that one nucleus can be in each of the new cells after the cell divides. In order to create two genetically identical nuclei, DNA inside of the nucleus must be copied or replicated. This occurs during the S phase of the cell cycle. During mitosis, the copied DNA is divided into two complete sets, so that after cytokinesis, each cell has a complete set of genetic instructions.
Four Phases of Mitosis:
*Prophase: The chromatin, which is unwound DNA, condenses forming chromosomes. The DNA becomes so tightly wound that you can see them under a microscope. The membrane around the nucleus, called the nuclear envelope, disappears. Spindles also form and attach to chromosomes to help them move.
*Metaphase: The chromosomes line up in the center, or the equator, of the cell. The chromosomes line up in a row, one on top of the next.
*Anaphase: The two sister chromatids of each chromosome separate as the spindles pull the chromatids apart, resulting in two sets of identical chromosomes.
*Telophase: The spindle dissolves and nuclear envelopes form around the chromosomes in both cells.
The DNA in the nucleus wraps around proteins to form chromosomes.
During mitosis, the newly duplicated chromosomes are divided into two daughter nuclei.
Mitosis occurs in four phases, called prophase, metaphase, anaphase, and telophase