cell cycle Flashcards
cell cycle
period of time between birth of a cell and its division into 2 daughter cells. End of mitosis 2 daughter cells are formed
2 parts of cell cycle
mitosis and interphase
interphase
the interval between the end of mitosis and the beginning of the next, cell is either resting or performing its specialized work. Parts of interphase = g1, s, g2
G1
Cells respond to growth factors directing the cell to initiate another cycle. once made decision is irreversible. Phase in which most of the molecular machinery is required. Can take less than 2 hours
G0
cells that retain the capacity for proliferation, but which are no longer dividing. They don’t enter S phase. Growth factors ca stimulate cells to leave G0 and re-enter cycle
S
relation of DNA to genes was established. DNA needs to replicate to have enough for 2 daughter cells. Therefore, new DNA is synthesized in this phase.
G2
end of S before mitosis. The cell prepares for division this ends with the breakdown of the nuclear membrane.
mitosis
Results in distribution of identical copies of the parent cell genome into 2 daughter cells. Replication of DNA takes place in chromosome.
4 stages on mitosis
prophase, metaphase, anaphase, telophase
prophase
individual chromosomes are visualized as thin threads and are tightly coiled. Each chromosome splits down the middle into 2 chromatids joined at centromere. The 2 centrioles are separated by elongation of microtubules, sand they occupy opposite poles of nucleus. Chromosomes now entangled in continuous microtubules
metaphase
centromere region of chromosome is called kinetochores. Microtubules are organized and extend to kinetochores from centrioles
anaphase
centromeres split down middle and chromatids separate forming 2 new chromosomes. Spindle fibers contract. 2 identical chromosomes are formed. Separation of chromatids occurs by contraction of microtubules which exert a centrifugal force into centromere region
telophase
reorganization period. Daughter cells are enveloped by new nuclear membrane and nucleolus appears. Chromosomes uncoil and their individual identity is lost. 2 complete cells are formed now. In process of cytokinesis the cleavage furrow develops.
