Cancer as an Example of Lack of Regulation

Tumors are tissue masses that arise through mutations in the genes that govern growth and division. Benign tumors are ones that grow slowly and remain in their original location.

Cancers are malignant forms of tumors. Malignant tumors grow rapidly, causing destructive effects on surrounding cells. Changes in DNA can be triggers for cancer. Malignant cells can break lose and migrate to other parts of the body (metastasis) to form additional tumors.

This animation (Audio - Important) shows how a malignant cell can break off from a cancer, enter the blood stream, and be transmitted to a different location where it initiates another malignant tumor.

In cancer, the plasma membrane and cytoplasm are altered. Cells grow and divide abnormally, and have a weakened capacity for adhesion to each other. They can break away and cause new cancers, and can be lethal unless eradicated. Oncogenes have the potential to induce cancer. They can form following insertions of viral DNA into DNA or after carcinogens change the DNA. They are mutated forms of normal genes. The normal versions are called proto-oncogenes.

There are a number of types of oncogenes and they have been given abbreviated names. There are genes that specify proteins that induce cell proliferation (for example: erb, src, myc). There are genes that inhibit cell proliferation (such as p53), and genes that suppress or trigger cell suicide

REVIEW: The spread of a cancer from one site to others in the body is known as
Answer metastasis.