second checkpoint is located at the end of G2 phase

   
The second checkpoint is located at the end of G2 phase, triggering the start of the M phase (mitotic phase). In order for this checkpoint to be passed, the cell has to check a number of factors to ensure the cell is ready for mitosis. If this checkpoint is passed, the cell initiates the many molecular processes that signal the beginning of mitosis. The CDKs associated with this checkpoint are activated by phosphorylation of the CDK by the action of a "Maturation promoting factor" (Mitosis Promoting Factor, MPF).
The molecular nature of this checkpoint involves an activating phosphatase, known as Cdc25, which under favorable conditions removes the inhibitory phosphates present within the MPF (term for the cyclin B/CDK1 complex). However, DNA is frequently damaged prior to mitosis, and, to prevent transmission of this damage to daughter cells, the cell cycle is arrested via inactivation of the Cdc25 phosphatase. This is done by the ATM kinase protein which phosphorylates Cdc25 which leads to its ubiquitinylation and destruction.

1 comment:

  1. My ex-husband and I had always managed to stay friendly after our divorce in February 2017. But I always wanted to get back together with him, All it took was a visit to this spell casters website last December, because my dream was to start a new year with my husband, and live happily with him.. This spell caster requested a specific love spell for me and my husband, and I accepted it. And this powerful spell caster began to work his magic. And 48 hours after this spell caster worked for me, my husband called me back for us to be together again, and he was remorseful for all his wrong deeds. My spell is working because guess what: My “husband” is back and we are making preparations on how to go to court and withdraw our divorce papers ASAP. This is nothing short of a miracle. Thank you Dr Emu for your powerful spells. Words are not enough. here is his Email: emutemple@gmail.com or call/text him on his WhatsApp +2347012841542

    ReplyDelete