AP BIOLOGY

Detailed explanation-1: -Unlike normal genes, oncogenes cannot be turned off, so they cause uncontrolled cell growth. In normal cells, tumor suppressor genes prevent cancer by slowing or stopping cell growth. DNA changes that inactivate tumor suppressor genes can lead to uncontrolled cell growth and cancer.

Detailed explanation-2: -Cancer is a disease in which some of the body’s cells grow uncontrollably. There are many different types of cancer, and each begins when a single cell acquires a genomic change (or mutation) that allows the cell to divide and multiply unchecked. Additional mutations can cause the cancer to spread to other sites.

Detailed explanation-3: -Study finds that high levels of a growth factor increases risk for several cancers. A study of almost 400, 000 British participants has identified a new link between raised levels of the growth factor IGF-1 and increased thyroid cancer risk and has confirmed associations with breast, prostate and colorectal cancer.

Detailed explanation-4: -An abnormal mass of tissue that forms when cells grow and divide more than they should or do not die when they should. Tumors may be benign (not cancer) or malignant (cancer). Benign tumors may grow large but do not spread into, or invade, nearby tissues or other parts of the body.

Detailed explanation-5: -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.