Multiple Choice
In eukaryotic cells, what molecular system primarily controls progression through the cell cycle at key checkpoints (e.g., G1/S and G2/M)?
26
views
16. Cell Division
Control of the Cell Cycle
Multiple Choice
In the control of the cell cycle, how do cyclin-dependent kinases (CDKs) directly promote cell division?
A
By forming active complexes with cyclins that phosphorylate specific target proteins to drive progression through cell-cycle checkpoints
B
By acting as DNA polymerases that replicate chromosomes during S phase
C
By degrading cyclins through ubiquitin ligase activity to permanently shut down cell-cycle transitions
D
By opening nuclear pores to allow chromosomes to enter the nucleus during mitosis
Verified step by step guidance1
Understand the role of cyclin-dependent kinases (CDKs) in the cell cycle: CDKs are enzymes that regulate progression through different phases of the cell cycle by modifying other proteins.
Recognize that CDKs require binding to cyclins to become active; cyclins are regulatory proteins whose levels fluctuate during the cell cycle.
Know that the active cyclin-CDK complexes phosphorylate specific target proteins, which triggers the cell to pass through critical checkpoints, such as the G1/S and G2/M transitions.
Realize that phosphorylation by cyclin-CDK complexes leads to changes in the activity of proteins involved in DNA replication, mitosis, and other cell cycle events, thus directly promoting cell division.
Eliminate incorrect options by understanding that CDKs do not act as DNA polymerases, do not degrade cyclins themselves (this is done by ubiquitin ligases), and do not open nuclear pores; their primary function is phosphorylation of target proteins when complexed with cyclins.
Related Videos
Related Practice
