An kinase enzyme that is active only when attached to a particular cyclin.Group of answer choicesMPFCdkcyclin

The question pertains to the relationship between kinases and cyclins in the regulation of the cell cycle. Specifically, it seems to focus on cyclin-dependent kinases (CDKs).

Explanation

1. Kinase Enzymes: These are enzymes that add phosphate groups to other molecules (often proteins) in a process called phosphorylation, which can activate or deactivate the target molecule.

2. Cyclins: These are proteins that regulate the cell cycle by activating cyclin-dependent kinases (CDKs). Cyclins must bind to CDKs for them to be active.

3. Cyclin-Dependent Kinases (CDKs): These kinases are only active when they are bound to a cyclin. This binding is crucial for the regulation of the cell cycle, ensuring that events such as DNA replication and cell division occur in a controlled manner.

Final Answer

The correct option is Cdk, as kinases (specifically CDKs) are active only when they are attached to a specific cyclin.