Question

Cancer cells often lack normal DNA damage response and cell-cycle control mechanisms. Why does this make them more susceptible to DNA-damaging chemotherapies? O Cancer cells will arrest in the cycle and will not grow further O Cancer cells with activating mutations in Ras will amplify the damage through the Ras signaling pathway Cancer cells might ignore the normal mechanisms that halt the cell cycle in response to damage, and subsequent division with damage leads to death, O Cancer cells have the ability to repair the DNA properly and thus will not accumulate mutations as quickly

Answer 1

1. Answer: (C) Cancer cells might ignore the normal mechanism that halt the cell cycle in response to DNA damage and subsequent division with damage leads to death.

In the history of cancer chemotherapy, DNA-damaging agents are in use. In normal cycle, DNA lesions are checked and leads to replication-associated DNA double-strand breaks (DSBs), when the cell cycle block replication fork progression. Cell will either under DNA repair and if cannot be repaired properly, cell death may result. But the cancer cells evade the cell cycle check points and have relaxed DNA damage-sensing/repair capabilities let them to proliferate despite the DNA damage which increases the probability of cell death.

2. Answer: (B) A component late in the pathway inhibit the enzyme early in the pathway.

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