Multiple Choice
Which of the following is NOT a function of S-Cdks?
16. Cell Division
G1 Phase
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What protein halts entry into S phase when DNA is damaged?
A
Mitogen
B
p53
C
S-Cdk
D
M-Cdk
Verified step by step guidance1
Understand the context: The cell cycle is regulated by checkpoints that ensure each phase is completed accurately before moving on to the next. The transition from G1 phase to S phase is one such checkpoint.
Identify the role of p53: p53 is a tumor suppressor protein that plays a critical role in preventing the cell from entering S phase if DNA damage is detected. It acts as a guardian of the genome.
Recognize the function of p53: When DNA damage is detected, p53 is activated and can induce cell cycle arrest, allowing time for DNA repair mechanisms to fix the damage before the cell proceeds to DNA replication in the S phase.
Differentiate between the options: Mitogens are signaling molecules that stimulate cell division, S-Cdk (S-phase Cyclin-dependent kinase) is involved in initiating DNA replication, and M-Cdk (M-phase Cyclin-dependent kinase) is involved in mitosis. None of these directly halt the cell cycle in response to DNA damage.
Conclude with the correct protein: Based on the role of p53 in halting the cell cycle in response to DNA damage, it is the correct answer to the question of which protein halts entry into S phase when DNA is damaged.
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