The cell cycle control system is similiar to a _____ and is regulated by _____ and _____ controls. ____ is the most important checkpoint resulting in _____ if given the "go ahead" or _____ if the cell does not recieve the "go-ahead" signal.
Internal and External
late G1; completion of S, G2, and M phases and will divide or enter G0 phase
MPF is _____ that is responsible for _____.
Maturation Promotion Factor is a Cyclin CDK complex that is responsible for cell passage past G2 checkpoint into M phase.
A cyclin is a _____. Cyclins work by ____.
Any protein whose concentration rises and falls during the Eukaryotic cell cycle.
Forming a complex with CDK, activating them, and determining their substrate speceficity.
_____ are the 3 types of regulators for CDK activity.
____ which, _____, is responsible for S-phase initiation.
SCF (Skp, Cullin, F-box containing complex), which is a ubiquitin protein ligase that marks s-phase inhibitors p27 and p21 for degredation.
(p21, 27 are cCDK inhibitors)
_____ are the 3 early steps of mitosis and are activated by _____ during _____ phase.
Nuclear envelope breakdown
Remodeling of mitotic spindle
_____ is responsible for allowing chromosomes to seperate during anaphase and works by ____.
MPF is a/an _____.
Cyclin-CDK heterodimer that is the KEY factor in regulating the initiation of Mitosis in all Eukaryotes
Describe regulation of Mitotic cyclin levels.
[MPF] high = s phase to M phase. At Metaphase APC/c polyUBq Securin = chromosome seperation.