cell cycle feedback control

[sarah90222]

im looking at the cell cycle. I know there are 3 check points — one between G1 and s, another before G2 and one during metaphase. My lecture notes say that cell cycle control involves both checkpoints and feedback control. I read on the internet that feedback control detects the failure to complete replication/repair/spindle assembly to arrest the progess of the cell cycle at one of the three checkpoints.

What i dont understand is, i thought that it was the checkpoints which detect failure using Cdks etc. So im just really confused about what feedback control is. i think it might be because i keep on thinking about what i studied back in school.Please can someone explain the feedback control to me in the cell cycle.

is feedback control the process ie using Cdks and other mechanisms but the check point is only a point in the cell cycle or position?

Thank you

[JackBean]

Basically, from definition, is feedback loop anything, what regulates previous steps in the pathway.
In the cell cycle, it can be APC complex, which degrades all cyclins and thus diminishes the activity of CDKs 😉

[kolean]

I don’t know if I would use the word ‘feedback control’, but it a name like anything else to be used as the process of the checkpoints.

Like in the S phase, all DNA has to be duplicated before moving on to the G2/M phase. Such as all stalled DNA replication forks will begin a process of signalling a protein (ATR), that will then activate a kinase (Chk1), that then phosphorylates and inactivates Cdc25(C) phosphatase. This phosphatase is important in dephosphorylating the inhibitory phosphate on the mitotic CDKs, which are needed for the cell to enter the M phase.

Thus, a feed back process of stalled DNA replication forks makes the mitotic-CDKs nonfunctional and the cell can not proceed into the M phase. And its control is at this particular checkpoint in the cell cycle.

[Author]

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