Mitosis and Meiosis: Flashcards
Early Prophase
Replicated chromosomes condense.
-Nuclear Envelope swells
Late Prophase
microtubules assembled and centrosomes begin to move apart
Metaphase
Chromosomes align forming metaphase plate
Early Anaphase
Cohesins degrade. Sister Chromatids separate
Late Anaphase
spindle poles move further part, further separating chromosomes
Telophase
Daughter nuclei form/ splits into two cells.
Centrosome
What Tubulin/Kinetochore Microtubules come from Lots of gamma-tubulin and stabilizing proteins in pericentrosome present
Astral Microtubules
Bind to cortex of cell to act as an anchor
How is centrosome duplication in S phase regulated?
CDK2-Cyclin E creates a phosphorylation cascade of proteins in pericentrosome space.. If abnormality is sensed, P53 kills cell, cell arrests, or if p53 is messed uptumor grows :(
Kinetochore
stabilizes tubulin at + end and binds to centromere
Centromere
In middle of chromosome but rather than regular histone, CENPA, is present. Cohesin cage surrounds centromere
3 Major Mitotic Kinases responsible for spindle formation and degredation:
Aurora Kinase A: in centrosome
Aurora Kinase B: localized in Kinetochore midzone
Polo like Kinase: found at centrosome and kinetochore
–>over expressed in cancer
What is Spindle Assembly Checkpoint?
MCC. Mitotic checkpoint complex: destabilizes attached kinetochore if only one side is attached. made of Bub1 and Bub3
APC (anaphase promoting complex)
- Inhibited by closed MAD w/ CDC 20 and BUB 1 and BUB 3 (MCC)
- However, MAD is opened. when kinetochore is attached to centromere, can ubiquinize CDC 20/BUb, causing their prtn interaction to be released
- –>this allows APC to destroy Cyclin B and Securin. Thus, allowing Anaphase
MAD
When closed, recruits CDC 20 and BUB 1 and BUB 3 (MCC) to APC to inhibit it
