During S the entire nuclear DNA is replicated. As replication is completed, S ends and the cell enters the final stage of interphase, G2. G2 is characterized by synthesis of a group of proteins necessary for progress through mitosis. Most cell types begin in G2 only briefly and the end of G2 marks the end of interphase and the beginning of mitosis. At the end of mitosis, two new cells are formed.
Mitosis is subdivided into four phases.
The four phases produce two identical daughter cells that resemble each other in every way. In mitosis the replicated cells contain the exact genetic makeup as the parent nucleus. The length of time it takes the cell to cycle depends on the organism involved and the conditions. From beginning to end, this process may take as little as 20 minutes to as much as several hours to complete. Most commonly, mitosis takes 24 hours.