As in prokaryotes, cell reproduction in eukaryotes entails reproductive signals, DNA replication, segregation, and cytokinesis. The details, however, are quite different:
Reproductive signal: Unlike prokaryotes, eukaryotic cells do not constantly divide whenever environmental conditions are adequate. In fact, most eukaryotic cells that are part of a multicellular organism and have become specialized seldom divide. In a eukaryotic organism, the signals for cell division are usually not related to the environment of a single cell, but to the function of the entire organism.
Replication: Whereas most prokaryotes have a single main chromosome, eukaryotes usually have many (humans have 46). Consequently the processes of replication and segregation are more intricate in eukaryotes than in prokaryotes. In eukaryotes, DNA replication is usually limited to part of the period between cell divisions.
Segregation: In eukaryotes, the newly replicated chromosomes are closely associated with each other (thus they are known as sister chromatids), and a mechanism called mitosis segregates them into two new nuclei.
Cytokinesis: Cytokinesis proceeds differently in plant cells (which have a cell wall) than in animal cells (which do not).
The cells resulting from mitosis are identical to the parent cell in the amount and kind of DNA they contain.
There is another mechanism for nuclear division called meiosis, which is involved in gamete formation. We will return to meiosis and describe differences with mitosis in Key Concept 11.5.