Download MITOSIS -Cells undergo cell division

MITOSIS
-Cells undergo cell division- to replace cells that have been lost due to
maturation/apoptosis
-cells also divide- inresponse to an increased work load
-seen by light microscope- labelled radioactive DNA precursors such as H3
Thymidine- recorded using autoradiographic methods
G0 phase
-most of the cells in this phase are differentiated- specific function
-to leave this phase requires growth factors
Progression through the cell cycle is dependent by cyclin dependent kinase which
phosphorylates other substrates and promote cell divison
G1
-longest and most variable cell cycle phase- determines the length of the whole
cycle
-requires continuous signals from growth factors
-large amount of growth- large amounts of RNA and protein synthesis
-restriction point at the end of G1 phase- determines whether cell can enter S
phase- cell size, condition of the chromosomes, external environment or enter the
G0 phase
-p53 stimulates the G1 phase to progress onto S phase
S
-all replication needed to create two cell occurs- DNA and organelles
-synthesis of DNA, replication of centrosomes
-centrosomes are key for cell division – each consists of two centiroles- barrels of 9
triplet microtubules
G2
-phase of chromosome packaging
-synthesis of proteins required for mitosis