What is the process by which cells reproduce, involving four distinct phases?

The process by which cells reproduce that involves four distinct phases is known as mitosis. Mitosis is a form of cell division that results in two daughter cells, each having the same number of chromosomes as the parent cell. This process is critical for growth, development, and tissue repair in multicellular organisms.

Mitosis is divided into four main phases: prophase, metaphase, anaphase, and telophase. During prophase, the chromatin condenses into visible chromosomes, and the nuclear envelope starts to break down. In metaphase, chromosomes align at the cell's equatorial plane. Anaphase follows, where sister chromatids are pulled apart to opposite poles of the cell. Lastly, during telophase, the chromosomes decondense, and the nuclear envelope re-forms around each set of chromosomes, ultimately leading to cytokinesis, where the cell divides into two.

While meiosis also involves a systematic cell division process, it specifically occurs in the production of gametes (sperm and eggs) and consists of two rounds of division, resulting in four non-identical cells. Cell differentiation refers to the process through which a less specialized cell becomes a more specialized cell type, and is not a reproductive process.