Final answer:
A loss of cell cycle checkpoints could lead to a normal cell becoming cancerous due to unchecked cell division and the accumulation of genetic damage, ultimately giving rise to tumors or leukemia.
Step-by-step explanation:
The change in a cell that would cause a normal cell to become an unregulated, cancerous cell is A. Loss of cell cycle checkpoints. When the cell cycle is no longer regulated properly due to changes in the DNA sequence of genes that code for regulatory molecules, cells may bypass these checkpoints, leading to continuous and uncontrolled division. Faulty instructions from mutated genes result in proteins that do not function as they should. Over time, this can lead to the accumulation of further damage and mutations as the altered cellular machinery no longer adequately monitors and repairs DNA. Subsequently, the unchecked division of these aberrant cells often results in the formation of tumors or blood cancer such as leukemia.
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