Today, the Railroad Retirement program is closely tied to the far better-known Social Security program, and although the Railroad Retirement program and Social Security share a number of common elements, key differences also exist between the two in areas such as funding and benefit structure.
The Cell Cycle. The cell cycle is the life cycle of a cell (Figure 5.3). At the end of the cell cycle, after mitosis has taken place, the parent cell no longer exists; it has given rise to two daughter cells. There are two phases in the cell cycle, interphase and mitosis.
Mitosis (M) encompasses just one step in the eukaryotic cell cycle: G 1 > S > G 2 > M > C. Cells grow during the dominant G 1 phase. Replication of chromosomes occurs in the S phase. Preparation for mitosis takes place during G 2 - replication of organelles and synthesis of microtubules.