Gamete formation involves a type of cell division called meiosis. This type of cell division reduces the number of sets of chromosomes from two in the parent cell to one in each gamete, counterbalancing the doubling that occurs at fertilization.
Mitosis is just one part of the cell cycle, the life of a cell from the time it is first formed during division of a parent cell until its own division into two daughter cells
Food and drugs can be sources of chemicals that act as exogenous ligands in cell communication. Exogenous ligands can disrupt the usual activity of a signal transduction pathway, thereby altering the responses of target cells.
Signal Transduction pathways differ in specific details, but have certain, unifying characteristics. All pathways follow a sequence: Reception,Transduction, Response