Cell division is a biological process that allows organisms to grow, develop, and maintain tissues. This process creates new cells from existing ones, ensuring the continuity of life. Mitosis is a type of cell division that increases cell number, facilitating growth, and enabling the repair and replacement of damaged cells. It also serves as a means of asexual reproduction in some organisms, producing genetically identical offspring.
How Mitosis Works
Mitosis involves a series of events that ensure accurate genetic distribution to new cells. Before division, the cell prepares its genetic information during interphase, specifically the S (synthesis) phase. Here, the cell duplicates its entire DNA set. This duplication results in each chromosome consisting of two identical copies, called sister chromatids, which remain joined.
Once the DNA is replicated, the cell enters the mitotic phase, which includes several distinct stages. During prophase, duplicated chromosomes condense and become visible. In metaphase, these chromosomes align in the center of the cell. In anaphase, sister chromatids separate and are pulled to opposite ends of the cell. Finally, during telophase, new nuclear envelopes form around the two sets of chromosomes at each pole, and the cell divides into two daughter cells through cytokinesis.
Chromosome Count in Daughter Cells
The daughter cells produced through mitosis are diploid. A diploid cell contains two complete sets of chromosomes, with one chromosome from each homologous pair inherited from each parent. Human somatic (body) cells are diploid and contain 46 chromosomes, arranged in 23 pairs. This number is represented as 2n, where ‘n’ denotes the number of chromosomes in a single set.
Mitosis is an equational division because it maintains the chromosome number. Prior DNA replication ensures that when the cell divides, each new cell receives a full complement of chromosomes. Each separated sister chromatid becomes an individual chromosome within the newly formed daughter cells, preserving the diploid state. The purpose of mitosis is to create more diploid cells that are genetically identical to the original parent cell.
This process contrasts with meiosis, another type of cell division that produces haploid cells. Haploid cells contain only one set of chromosomes, or half the number found in diploid cells. In humans, gametes, such as sperm and egg cells, are haploid and contain 23 chromosomes. Meiosis is a reductional division for sexual reproduction, where two haploid cells combine during fertilization to restore the diploid chromosome number in the offspring.