Cell Cycle: Differentiation

Cell Cycle

The life cycle of each cell is regulated via stimulation from hormones or growth factors. Disruption of the cycle can affect the health of the body. Most human cells divide from 40 to 60 times before they die. The life cycle of a cell includes the following steps:

■■ Interphase: The cell obtains nutrients to grow andduplicate. This is actually the period from cell for mation to cell division. This step may be betterunderstood as being a metabolic or growth phase.

■■ Cell division (mitosis): The nucleus divides.

■■ Cytoplasmic division (cytokinesis): The cytoplasmdivides.

■■ Differentiation: The cell becomes specialized.

Differentiation

Differentiation, the process of specialization of a cell, makes each cell unique. New cells must be generated for growth and tissue repair to occur. Stem cells are those that can divide repeatedly without specializing. They can divide either into two identical daughter cells or so that one daughter cell becomes partially special-ized (progenitor cells). In the human body, all differ-entiated cell types are created because of the variance of stem and progenitor cells.

Stem cells in certain organs may have the ability to heal the body in the future, even though they were differentiated when the organism was still an embryo or fetus. As the body continually develops, cells use different parts of complete genetic instructions so they can become specialized. Genes may be activated in various types of cells.