1G1/S Cyclins
Cyclin E, binds CDK2 at end of G1 and commit the cell to DNA replication.
2S Cyclins
Cyclin A, Binds CDK2 during Sphase and are required for the initiation of DNA replication.
3Describe all DNA checkpoints:
G1 - Ensures a favorable environment and proceeds to the S phase
G2/M - Ensure favorable environment and all DNA is replicated proceed to the M phase
M - Ensures all chromosomes are attached to spindle, triggers anaphase and proceed to Cytokinesis.
4M Cyclins
Cyclin B binds Cdk 1 and promotes events in mitosis.
5G1 Cyclins
Cyclin D binds CDK 4 and 6, promoting passage through start restriction point in late G1
6CKI
CDK Inhibitor is an uncompetitive inhibitor that binds to an allosteric site and inactivates the CDK active site.
7What does increased CDK activity at the beginning of mitosis lead to?
Phosphorylation of proteins that control chromosome condensation, caused by increased production of cyclin proteins.
8How does S-Cdk prevent rereplication?
Phosphorylates Cdc6, which dissociates and dismantles the PreRC. Mcm or helicase also dissociates preventing rereplication after sphase.
9What is the purpose of MCdk?
Induces the assembly of the mitotic spindle and ensures that replicated chromosomes attach to the spindle. Triggers nuclear breakdown and chromosome condensation.
10APC?
Initiates sister chromatid separation. APC targets securin proteins. Securin/Separase complex cleaves cohesin proteins that keep sister chromatids together.