The cell cycle
The cell cycle is an ordered set of events that leads to cell growth and division into two daughter cells. The cell cycle begins the moment a new cell appears, a descendant of another that divides, and ends at the moment when said cell, by division, originates two new daughter cells.
The duration of the cell cycle depends on the type of cell, and can be from a few hours to years. Eukaryotic beings multicellular can have two types of cells: diploid and haploid.
All cells have to be born and die. Multicellular beings can live longer than the cells that compose them, so cells have to reproduce at least at the same rate as they die.
Throughout the cell cycle, from when the cell appears until it divides into two other cells, the cell goes through two different stages:
- Interphase: a long stage of cell growth, in which the cell duplicates its DNA, synthesizes proteins, produces the necessary organelles, and prepares for cell division. It covers the time elapsed between two successive divisions. It is divided into three phases, although some remain in another phase called G0 that will be seen later:
- The G phase 1 means "gap 1", corresponds to the interval 1.
- The S phase represents "synthesis", in which DNA replication occurs.
- The G phase 2 , of "gap 2" corresponds to the range 2.
- Mitosis, cell division or M phase: short stage in which chromosomes appear. The two new daughter cells are formed from one cell. It's divided in: