BSC 1010 Chapter Notes - Chapter 19: Hematopoietic Stem Cell, G1 Phase, G2 Phase
Document Summary
Mitosis is a relatively short part of the cell cycle. Cells spend very little time in m phase. Most of the time is spent in interphase. Composed of: g1 phase, s phase (when dna is replicated), and g2 phase. The overall length of the cell cycle is called the generation time: 18-24 hours in cultured mammalian cells. Cell cycle length varies among different cell types. Some cells have long generation times or do not divide at all: cells that exit the cell cycle entirely are said to undergo terminal differentiation, highly specialized cells. Include nerve cells, muscle cells, or red blood cells. Some cells divide continuously: skin and internal epithelial cells, basal layer, hematopoietic stem cells, spermatogonia. Some cells do not divide unless stimulated: examples: liver cells and lymphocytes. Quiescence (g0: not actively dividing but capable to do so if conditions change, cells usually arrested prior to dna synthesis.