Prometaphase: Difference between revisions
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[[File:PLoSBiol3.5.Fig1bNucleus46Chromosomes.jpg|thumb|200px|The 23 human chromosome territories during prometaphase in [[fibroblast]] cells.]] |
[[File:PLoSBiol3.5.Fig1bNucleus46Chromosomes.jpg|thumb|200px|The 23 human chromosome territories during prometaphase in [[fibroblast]] cells.]] |
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<!-- Deleted image removed: [[Image:Prometaphase-flourescent2.jpg|thumb|160px|In late prometaphase, most of the chromosomes have begun the events of [[metaphase]] while the rest should have at least have one kinetochore connected.]] --> |
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'''Prometaphase''' is the phase of [[mitosis]] following [[prophase]] and preceding [[metaphase]], in [[eukaryote|eukaryotic]] [[somatic]] [[Cell (biology)|cell]]s. Prometaphase is sometimes simply included as part of the end of prophase and early metaphase. |
'''Prometaphase''' is the phase of [[mitosis]] following [[prophase]] and preceding [[metaphase]], in [[eukaryote|eukaryotic]] [[Somatic (biology)|somatic]] [[Cell (biology)|cell]]s. Prometaphase is sometimes simply included as part of the end of prophase and early metaphase. |
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In prometaphase, the [[nuclear membrane]] breaks apart into numerous "membrane vesicles", and the chromosomes inside form protein structures called [[kinetochores]].<ref name="Nature Education">{{cite web|title=prometaphase|url=http://www.nature.com/scitable/definition/prometaphase-281|publisher=Nature Education|accessdate=9 December 2012}}</ref> Kinetochore microtubules emerging from the centrosomes at the poles (ends) of the spindle reach the chromosomes and attach to the kinetochores,<ref name="Nature Education" /> throwing the chromosomes into agitated motion.{{citation needed|date=December 2012}} Other spindle microtubules make contact with microtubules coming from opposite pole. Forces exerted by protein "motors" associated with spindle microtubules move the chromosomes toward the center of the cell. |
In prometaphase, the [[nuclear membrane]] breaks apart into numerous "membrane vesicles", and the chromosomes inside form protein structures called [[kinetochores]].<ref name="Nature Education">{{cite web|title=prometaphase|url=http://www.nature.com/scitable/definition/prometaphase-281|publisher=Nature Education|accessdate=9 December 2012}}</ref> Kinetochore microtubules emerging from the centrosomes at the poles (ends) of the spindle reach the chromosomes and attach to the kinetochores,<ref name="Nature Education" /> throwing the chromosomes into agitated motion.{{citation needed|date=December 2012}} Other spindle microtubules make contact with microtubules coming from opposite pole. Forces exerted by protein "motors" associated with spindle microtubules move the chromosomes toward the center of the cell. |
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Revision as of 17:05, 2 December 2014
Prometaphase is the phase of mitosis following prophase and preceding metaphase, in eukaryotic somatic cells. Prometaphase is sometimes simply included as part of the end of prophase and early metaphase.
In prometaphase, the nuclear membrane breaks apart into numerous "membrane vesicles", and the chromosomes inside form protein structures called kinetochores.[1] Kinetochore microtubules emerging from the centrosomes at the poles (ends) of the spindle reach the chromosomes and attach to the kinetochores,[1] throwing the chromosomes into agitated motion.[citation needed] Other spindle microtubules make contact with microtubules coming from opposite pole. Forces exerted by protein "motors" associated with spindle microtubules move the chromosomes toward the center of the cell.
Types of microtubules
The microtubules are composed of two types, kinetochore microtubules and non-kinetochore microtubules.
- Kinetochore microtubules begin searching for kinetochores to attach to.
- A number of non-kinetochore microtubules or polar microtubules find and interact with corresponding nonkinetochore microtubules from the opposite centrosome to form the mitotic spindle.
Transition from prometaphase to metaphase
The role of prometaphase is completed when all of the kinetochore microtubules have attached to their kinetochores, upon which metaphase begins. An unattached kinetochore, and thus a non-aligned chromosome, even when most of the other chromosomes have lined up, will trigger the spindle checkpoint signal. This prevents premature progression into anaphase by inhibiting the anaphase-promoting complex until all kinetochores are attached and all the chromosomes aligned.[2]
Early events of metaphase can coincide with the later events of prometaphase, as chromosomes with connected kinetochores will start the events of metaphase individually before other chromosomes with unconnected kinetochores that are still lingering in the events of prometaphase.[citation needed]
References
- ^ a b "prometaphase". Nature Education. Retrieved 9 December 2012.
- ^ May, Karen M; Kevin G. Hardwick (2006). "The spindle checkpoint". Journal of Cell Science. 119 (Pt 20): 4139–42. doi:10.1242/jcs.03165. PMID 17038540. Retrieved 9 December 2012.
External links
Media related to Prometaphase at Wikimedia Commons
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