dentify all the false statements. 1. CDK's confer target specificity to cyclin / CDK activity. 2. Cyclins activate CDKs. 3. Only one cyclin is required per cell cycle. 4. CDK's are destroyed by the ubiquitination apparatus. 5. The concentration of a CDK changes less than a cyclin during a cell cycle.

Only 3rd statement is false

Explanation:

CDK's confer target specificity to cyclin/CDK activity-This statement is true because in the cell cycle cyclin-dependent kinases (Cdks) process signals that lead to cell division Cyclins activate CDKs-This statement is true because cyclin is the regulatory subunit which binds to CDKs and activate them Only one cyclin is required per cell cycle-This statement is false because there are many types of cyclins per cell cycle; for example G1 cyclins (Cyclin D and E), S phase cyclins (Cyclin A) and mitotic cyclin (Cyclin B) CDKs are destroyed by the ubiquitination apparatus-This statement is true because degradation of CDKs occurs through polyubiquitination The concentration of a CDK changes less than a cyclin during a cell cycle-This statement is true because during the cell division cyclins are periodically synthesised whereas CDKs concentration remains constant