Indirect division, divided into anterior, middle and posterior stages according to the morphology and structure of mitosis C

① Prophase: chromatin condensation (start mark), division pole determination, nucleolus shrinkage, spindle formation (temporary C apparatus, astral microtubules, kinetochore microtubules, overlapping microtubules)

② Metaphase: The chromosomes are condensed to the greatest extent and randomly arranged on the equatorial plate to form the mitotic apparatus.

③Later stage: the two sister chromatids separate and move to the cell level

④Telophase: Nuclear formation and cytokinesis of daughter cells, chromosome decondensation, nucleolus re-formation, and nuclear membrane reconstruction

DNA replicates only once, while cells divide twice in succession

①The first meiosis: completes the halving of chromosome number and the exchange of genetic material

②Short interval

③Second meiosis: prophase II, metaphase II, anaphase II, telophase II, and cytokinesis

Direct division, the nuclear membrane does not disappear, no spindle formation and chromosome assembly

The pattern that a cell goes through from the end of its last division to the end of its next division

①G1 phase: synthesis of RNA and ribosomes, 12~32h, critical

②S phase: synthesis of genetic material, DNA, histones and enzymes required for replication, replication of centrioles

③G2 phase: A large amount of RNA and protein (tubulin) are synthesized, mitosis preparation phase

core

Cell cycle checkpoints monitor cell cycle operations

Various factors are related to cell cycle regulation

Physiological regeneration: maintain cell number constant renewal, stem cell division

Compensatory regeneration: highly differentiated tissues are repaired after damage, stimulating G0 phase cells to return to the cell cycle, and the cell cycle is accelerated.