This post includes summaries from Cell cycle lectures in Molecular Biology given by PhD. Jamlec de la Vega (Fall, 2011) at Tecnológico de Monterrey Campus Puebla. The intention is helping in the study of the most important concepts of this topic and making an overall list of each stage and the relevant done in each one.
– Asexual reproduction (Prokaryotes replication called binary fission)
– Multi cellularity (Eukariotes replication and sorting process)
Interphase: (Sister chromatids formed)
– G1 (Checkpoint) Nutrients are gathered for replication.
– S Replication occurs. Kinetochore proteins formed at centromere of sister chromatids.
– G2 (Checkpoint) Nutrients are gathered for nuclear and cell division.
– Prophase. Sister chromatids condensed and nuclear envelope fragments. Mitotic spindle apparatus.
– Prometaphase. Centrioles reach opposite poles pulled by aster microtubules and pushed by polar ones, and sister chromatids are fully condensed and attached by kinetochores.
– Metaphase (Checkpoint, alignment at mitotic plate)
– Anaphase (Centromeres break apart and start to be pulled by polar microtubules to each side of the centrioles.)
– Telophase (Nuclear envelopes start forming and cytokinesis starts.)
2 Mitosis Phases
>Leptotene (sister chromatids condenses)
>Zygotene (Synaptonemal complex)
>Pachytene (Crossing over)
>Diplotene (Chiasma, tetrad and dissolution of synaptonemal complex)
>Diakinesis (Nuclear envelope fragmenting)
* At metaphase I the metaphase plate compared with the one present in metaphase and metaphase II is ordered differently: In the first case bivalents (two homologue chromosomes) are formed in tetrads making pairs one beside the otherand the microtubules are binded to one of homologue centromere to each pole, whereas in the second ones a single line of chromosomes is present and the microtubules of each pole bind to the same centromere making it break appart and not just separating one homologue chromosome from the other.
** Starting point of Prophase II is half of the genetic material as in Prophase.
Cytokisesis. Cleavage furrow forms and cell membrane finishes its division.
In Check points Cycline-dependant kisases revise the availability of Specific checkpoint Cycline in the cell and continue, delay or cancel the advance a step in the cycle.