AP BIOLOGY

Detailed explanation-1: -If a checkpoint fails or if a cell suffers physical damage to chromosomes during cell division, or if it suffers a debilitating somatic mutation in a prior S phase, it may selfdestruct in response to a consequent biochemical anomaly. This is another example of apoptosis.

Detailed explanation-2: -Overexpression of growth factors or a lack of suppressor proteins can lead to rapid uncontrolled cell division. As cells proliferate without regulation, tumors occur that can become deadly if not treated.

Detailed explanation-3: -Cancer is the result of unchecked cell division caused by a breakdown of the mechanisms regulating the cell cycle. The loss of control begins with a change in the DNA sequence of a gene that codes for one of the regulatory molecules.

Detailed explanation-4: -Cell cycle checkpoints are critical to prevent the cell from progressing to the next phase of the cell cycle before the prior phase has been completed. Premature entry into the next phase of the cell cycle can result in catastrophic consequences for the cell and cell death.