Question

The following schematic shows the activation of M-Cdk in mitosis. Indicate which proteins below correspond to those indicated as A to D in the diagram.

Answer 1

In mitosis, cyclins and cyclin-dependent kinases (Cdks) form complexes that must be phosphorylated for full activation, allowing the cell to progress through the cell cycle.

Step-by-step explanation:

The activation of M-Cdk in mitosis involves a complex interplay between proteins known as cyclins and cyclin-dependent kinases (Cdks). Cyclins regulate the cell cycle by binding tightly to Cdks. Once bound, the Cdk/cyclin complex must be phosphorylated by another kinase for full activation. Phosphorylation changes the shape and thus activates the protein, allowing it to then phosphorylate other proteins, which are involved in advancing the cell to the next phase of the cell cycle. Cyclin levels fluctuate during the cell cycle, determining when Cdk/cyclin complexes form, and these complexes are essential for regulating different checkpoints.