Anaphase
Anaphase (from
Anaphase starts when the
At this point, three subclasses of microtubule unique to mitosis are involved in creating the forces necessary to separate the chromatids: kinetochore microtubules, interpolar microtubules, and astral microtubules.
The centromeres are split, and the sister chromatids are pulled toward the poles by kinetochore microtubules. They take on a V-shape or Y-shape as they are pulled to either pole.
While the chromosomes are drawn to each side of the cell, interpolar microtubules and astral microtubules generate forces that stretch the cell into an oval.[3]
Once anaphase is complete, the cell moves into telophase.[4]
Phases
Anaphase is characterized by two distinct motions. The first of these, anaphase A, moves chromosomes to either pole of a dividing cell (marked by centrosomes, from which mitotic microtubules are generated and organised). The movement for this is primarily generated by the action of kinetochores, and a subclass of microtubule called kinetochore microtubules.
The second motion, anaphase B, involves the separation of these poles from each other. The movement for this is primarily generated by the action of interpolar microtubules and astral microtubules.
Anaphase A
A combination of different forces have been observed acting on chromatids in anaphase A, but the primary force is exerted centrally. Microtubules attach to the midpoint of chromosomes (the centromere) via protein complexes (kinetochores). The attached microtubules depolymerise and shorten, which together with motor proteins creates movement that pulls chromosomes towards centrosomes located at each pole of the cell.[5]
Anaphase B
The second part of anaphase is driven by its own distinct mechanisms. Force is generated by several actions. Interpolar microtubules begin at each centrosome and join at the equator of the dividing cell. They push against one another, causing each centrosome to move further apart. Meanwhile, astral microtubules begin at each centrosome and join with the cell membrane. This allows them to pull each centrosome closer to the cell membrane. Movement created by these microtubules is generated by a combination of microtubule growth or shrinking, and by motor proteins such as dyneins or kinesins.[6]
Relation to the cell cycle
Anaphase accounts for approximately 1% of the
See also
References
- ^ "Chromosome condensation through mitosis". Science Daily. Retrieved 12 June 2007.
- ^ "The Cell Cycle". Kimball's Biology Pages. Archived from the original on 2012-11-19. Retrieved 9 December 2012.
- PMID 16488869.
- S2CID 43902779.
- PMID 28218660.
- PMID 27941648.
- PMID 7398661.
External links
- Media related to Anaphase at Wikimedia Commons