객관식
Which of the following statements about red blood cells (erythrocytes) is correct?
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11. Cell Division
Cell Cycle Regulation
객관식
Which protein complex is primarily responsible for regulating the transition from the G1 phase to the S phase in the eukaryotic cell cycle?
A
p53-MDM2 complex
B
Cyclin E/CDK2
C
Cyclin B/CDK1
D
Cyclin D/CDK4
검증된 단계별 안내1
Understand the eukaryotic cell cycle: The cell cycle consists of four main phases: G1, S, G2, and M. The G1 phase is the first gap phase where the cell grows and prepares for DNA replication, which occurs in the S phase.
Learn about cyclins and CDKs: Cyclins are regulatory proteins that bind to cyclin-dependent kinases (CDKs) to activate them. These complexes play a critical role in controlling the progression of the cell cycle by phosphorylating target proteins.
Focus on the G1 to S phase transition: The transition from G1 to S phase is tightly regulated to ensure the cell is ready for DNA replication. Cyclin D/CDK4 is the primary complex responsible for this transition by phosphorylating the retinoblastoma protein (Rb), which releases E2F transcription factors to initiate S phase gene expression.
Differentiate between the listed complexes: Cyclin E/CDK2 is involved later in the G1 phase and helps finalize the transition to S phase. Cyclin B/CDK1 is associated with the G2 to M phase transition. The p53-MDM2 complex is involved in cell cycle arrest and apoptosis, not the G1 to S phase transition.
Conclude with the correct complex: Cyclin D/CDK4 is the key protein complex that regulates the transition from the G1 phase to the S phase by phosphorylating Rb and promoting the activation of genes required for DNA replication.
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