Microtubule organizing centers (aka centrosomes) are composed of asters at each end, with centrosomes spanning […]


Metaphase checkpoint How does the metaphase checkpoint prevent sister chromatid separation at the onset of […]


Mitosis is the division of a parent cell into two daughter cells that are identical […]

Mitosis factors

FactorOverview E2FE2F is a transcription factor that by itself activates transcription. RbRb binds to E2F […]

Mitosis Promoting Factor

Cycles in M-Phase Promoting Factor (MPF) activity control mitosis. As a protein kinase, MPF likely […]

Mitosis: Biochemical Pathways

An obvious advantage of proteolysis for controlling passage through these critical points in the cell […]

Mitosis: Cell Cycle Activators

HumanYeastActivatesOverview CAK KinaseCyclin-CDKsCAK positive phosphorylates CDK1, CDK2 and CDK4. CAK is itself a member of […]

Mitosis: Cell Cycle Inhibitors

HumanYeastInhibitsOverview Wee1 KinaseCyclin-CDKsInhibitory phosphorylation of CDK1 and CDK2. (link INK4Mid-G1 CDKsINK4s include cyclin-dependent kinase 4 […]

Mitosis: Cyclin-CDKs

Cyclin-dependent kinases regulate two important transitions in the eukaryotic cell cycle: entry into S-phase and […]

Mitosis: Ubiquitin Protein Ligases

Polyubiquitination marks eukaryotic proteins for degradation by proteasomes. Three enzymes are required for the Ubiquitin […]

Mitosis: Vertebrate Checkpoints

CheckpointOverview DNA Damage AMidway through G1, ATM/R activates p53, which activates p21CIP, which blocks Mid-G1-Cyclin+CDK […]


Nondisjunction is a rare event that occurs in when paired homologous chromosomes or sister chromatids […]

Synthesis (S) phase

Eukaryotic chromosomes are replicated from multiple origins. Initiation of replication from these origins occurs throughout […]


How is the dismantling of the nuclear lamina during prophase and its reassembly during telophase […]

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