Question

an important checkpoint regulator is at the gap2/m-phase transition. here cyclin B and cdk1 activate and form MPF which becoes a ________ two words and causes the DNA to condense into_____

Answer 1

An important checkpoint regulator is at the gap2/m-phase transition. here cyclin B and cdk1 activate and form MPF which becoes a positive feedback two words and causes the DNA to condense into chromosome.

gap2/ m-phase transition checkpoint checks for damage DNA or incomplete replication. Once damage DNA or incomplete replication is found, ATM and ATR recruited to damage site which causes activation of chk1 and chk2 as well as p53 activation occurs which ultimately results in cell arrest. In case of no damage or complete replication, activation of cyclinB-cdk1 occurs by various mechanisms. CyclinA-Cdk2 activates Cdc25, an activator of cyclinB-Cdk1, which then deactivates the cyclinB-Cdk1 inhibitor, Wee1. This results in a positive feedback loop, significantly increasing cyclinB expression and Cdk1 activation. This increased expression of cyclin B and cdk1 form MPF (mitosis promoting factor) which cause the DNA to condense into chromosome. The condesation of DNA (chromatin) into chromospmes is initial requirement to begin mitosis.