The cells of all living organisms have characteristics in common, as well as many differences. One commonality is the ability to grow and reproduce through the production of new cells; cell division. Binary fission and mitosis are both methods of cell division used by various organisms. Binary fission is used exclusively by prokaryotic organisms, or bacteria. Mitosis on the other hand, is used by eukaryotic organisms, such as plants and animals. These cell division processes do share similarities, but close examination reveals a more intricate process during mitosis. The necessity for more complex cell division becomes clear when examining the differences between prokaryotic and eukaryotic cells.
Prokaryotic and Eukaryotic Cells
Prokaryotic cells are quite simple in structure. They have no nucleus, no organelles and only a small amount of DNA -- deoxyribonucleic acid -- in the form of a single, circular chromosome. Eukaryotic cells, on the other hand, have a nucleus, multiple organelles and more DNA arranged in multiple, linear chromosomes. The larger, multiple chromosomes that are contained within the nucleus of eukaryotic cells require a careful, step-by-step process to make sure that each chromosome is properly delivered to each new cell.
Similarities in Cell Division
All cells have DNA that must be copied, segregated and distributed to new cells in an organized fashion. Both mitosis and binary fission accomplish this. The process begins when new cells are needed. The cell grows larger, makes copies of all components, and then replicates the DNA. Replicated DNA is allocated equally to the new cells and the cell splits in half. This splitting is called cytokinesis.
Prokaryotic Binary Fission
In prokaryotes, which only have one chromosome, the DNA is replicated and each of the two chromosomes then separate and migrate to opposite ends of the cell. The “parent cell” then divides in the middle to form two “daughter cells,” each with a copy of the single chromosome. This division is a type of asexual reproduction, as each new cell contains an exact copy of the parent cell DNA.
Within the somatic, or non-sex, cells of eukaryotic organisms, mitosis occurs when the organism needs to grow, replace cells or repair damage. There are five steps to mitosis: prophase, prometaphase, metaphase, anaphase and telophase. These steps are defined by condensing DNA into chromosomes, followed by temporary removal of the nuclear membrane, separation of newly copied chromosomes, and movement of separated chromosomes to opposite ends of the cell. During telophase, nuclear membranes are then reformed around each cluster of separated chromosomes. Cytokinesis occurs after telophase. It should be noted that this process only occurs in somatic cells, with meiosis being the process for sex cells, such as eggs and sperm.