Introduction

An essential feature of living cells is their potential to replicate and produce exact copies of themselves. In single-celled organisms replication is achieved by cell division. In multicellular organisms programmed cell division is essential for growth and normal development. In this case, cell proliferation can be seen as a strategy for increasing overall size as well as permitting cells or groups of cells to specialize. Multicellular animals, plants and fungi, therefore, can develop different tissues each containing one or more cell types adapted to a particular function.

The coordination of the various processes required to bring about successful cell division is not trivial. Simply cutting a cell in two is unlikely to result in the production of two viable daughter cells (the products of a cell division). Mistakes at any stage during the entire division cycle can lead to mutant or non-viable daughter cells. To produce two viable cells from one, partitioning of all the necessary cellular components into the two daughters is essential. Each daughter must receive a complete copy of the genome of its mother cell (the cell undergoing division) if genetic integrity is to be maintained through subsequent generations. The genome contains the complete set of genetic information that encodes the proteins required for viability. This information is packaged into a set of chromosomes. The fidelity of replication of these chromosomes must be high in order to maintain genetic stability. Incomplete replication may lead to the loss of essential genes and, ultimately, death of daughter cells.