Mitosis is cellular division in which one parent cell divides into two daughter cells. It makes more copies of somatic (body) cells, as opposed to meiosis that makes sex cells. Therefore, mitosis maintains the number of chromosomes from parent to daughter cells. The steps of mitosis, in order, are prophase, metaphase, anaphase, and telophase.
Towards the beginning of prophase, DNA replicates. Thus, each chromosome duplicates (makes a copy) if itself. During DNA replication DNA is unzipped by an enzyme called helicase. Small proteins called single strand binding proteins (SSBs) keep the DNA from closing. Meanwhile, DNA polymerase travels down the length of DNA in the 3' n--> 5'direction and adds new complementary nucleotides to the strand (A to T and G to C). Ligase links the smaller fragments together to form one long complementary strand of DNA to the template strand.
During prophase, the chromosomes condense and become visible. These chromosomes line up in the middle of the cell during metaphase. The duplicated chromosomes are pulled apart from one another during anaphase. During telophase, the cell begins to furrow (split). Finally, the parent cell is cut into two daughter cells during cytokinesis.