CELL DIVISION

The cell (from Latin cella, meaning "small room" is the basic structural, functional, and biological unit of all known living organisms. Cells are the smallest unit of life that can replicate independently, and are often called the "building blocks of life". The study of cells is called cell biology.

Cell division is the process by which a parent cell divides into two or more daughter cells

Cell division usually occurs as part of a larger cell cycle

there are two distinct types of cell division:

Mitosis is a part of the cell cycle process by which chromosomes in a cell nucleus are separated into two identical sets of chromosomes, each in its own nucleus. In general, mitosis (division of the nucleus) is often followed by cytokinesis, which divides the cytoplasm, organelles and cell membrane into two new cells containing roughly equal shares of these cellular components. Mitosis and cytokinesis together define the mitotic (M) phase of an animal cell cycle—the division of the mother cell into two daughter cells, genetically identical to each other and to their parent cell.

Meiosis is a specialized type of cell division which reduces the chromosome number by half. This process occurs in all sexually reproducing eukaryotes (both single-celled and multicellular) including animals, plants, and fungi.

In meiosis, DNA replication is followed by two rounds of cell division to produce four daughter cells with half the number of chromosomes as the original parent cell. The two meiotic divisions are known as meiosis I and meiosis II. Before meiosis begins, during S phase of the cell cycle, the DNA of each chromosome is replicated so that it consists of two identical sister chromatids attached at a centromere.

Both of these cell division cycles are in sexually reproducing organisms at some point in their life cycle, and both are believed to be present in the last eukaryotic common ancestor

For simple unicellular organisms such as the amoeba, one cell division is equivalent to reproduction – an entire new organism is created

On a larger scale, mitotic cell division can create progeny from multicellular organisms, such as plants that grow from cuttings

Cell division also enables sexually reproducing organisms to develop from the one-celled zygote, which itself was produced by cell division from gametes.

And after growth, cell division allows for continual construction and repair of the organism

A human being's body experiences about 10,000 trillion cell divisions in a lifetime.