Identify the anti-neoplastic medication that is specific to a particular phase of the cell cycle ?
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Answer: C. Methotrexate
Explanation
Methotrexate acts as a dihydrofolate reductase inhibitor during DNA synthesis. It halts cellular replication by preventing nucleotide production specifically during S-phase. This precise timing categorizes it as a cell cycle-specific chemotherapeutic agent. The cell cycle consists of distinct phases governing cellular growth and division. S-phase is the specific period during which cellular DNA replication occurs. Antimetabolites mimic normal cellular substrates to disrupt key metabolic pathways.
Oncologists use cell-cycle specific drugs to target rapidly dividing cancer cell populations. Rapidly dividing normal tissues like bone marrow also experience collateral toxicity. Therapeutic protocols schedule doses carefully to maximize tumor destruction and recovery. Cyclophosphamide is an alkylating agent that acts nonspecifically across the cell cycle. Doxorubicin is an anthracycline antibiotic functioning across multiple cell cycle phases. Cisplatin crosslinks DNA strands, exerting cytotoxic effects throughout the entire cycle.
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