Question

Which of the following best describes the effect of cancer-causing mutations on the cell cycle? The mutations increase the speed of the cycle. The mutations cause the cell to bypass checkpoints in the cycle The mutations eliminate one or more stages of the cycle. The mutations interfere with S stage of the cycle. None of these.

Answer 1

Answer:

None of these.

Explanation:

Cancer mutations affect cell cycle regulators.

Cell cycle is a highly regulated process by the regulators that can promote cell cycle or inhibit the cycle. Genes that encode for those regulators are classified into two groups:

• proto-oncogenes-encode for positive regulators such as growth factor receptor. If a cancer mutation occurs in the proto-oncogene it becomes oncogene and its product is overactivated. The increased avtivity of positive regulators leads to abnormal cell division.
• tumor suppresor-the products of such genes blocks the cell cycle, but after the mutation they become inactive, which leads to uncontrolled cell cycle.