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Cell cycle regulation (cyclins, checkpoints) Transitional Reasoning Practice

Biology · Cell Communication & the Cell Cycle · Biology · Cell Cycle & Cell Division

1 Biology practice questions on Cell cycle regulation (cyclins, checkpoints). Questions that build towards applied reasoning.

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  1. 1.

    In an experiment investigating cell cycle checkpoints, cultured mammalian cells are treated with a targeted peptide inhibitor that selectively blocks the proteolytic degradation of M-cyclin (cyclin B) without affecting the ubiquitination of securin. Biochemical analysis confirms that cyclin-dependent kinase 1 (Cdk1) remains continuously bound to its regulatory cyclin partner and retains high kinase activity. Based on this molecular intervention, which of the following outcomes will be directly observed in the treated cell population?

    • A) The cells will enter mitosis and separate their sister chromatids but will fail to exit M phase and reform daughter nuclei.
    • B) The cells will immediately arrest at the G1 checkpoint because active Cdk1 will prevent the transcription of G1/S cyclins.
    • C) The cells will arrest at the G2/M boundary because constant M-cyclin binding blocks the phosphorylation of target structural proteins.
    • D) The cells will complete cytokinesis normally but will skip interphase and instantly begin a second round of sister chromatid separation.

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