Understanding the Basics of Cancer
Cancer is a disease of multicellular organisms that is characterized by uncontrolled cell division.
At least 80% of all human cancers are related to exposure to carcinogens, which are agents that increase the likelihood of developing cancer.
Most carcinogens, such as UV light and certain chemicals in cigarette smoke, are mutagens that promote genetic changes in somatic cells.
These DNA alterations can lead to effects on gene expression that ultimately affect cell division, and lead to cancer.
The development of cancer is a multistep process. Cancers originate from a single cell. This single cell and its line of daughter cells undergo a series of mutations that causes the cells to grow abnormally.
At an early stage, the cells form a tumor, which is an overgrowth of cells that serves no useful purpose. For most types of cancer, a tumor begins as a precancerous or benign growth.
This may be followed by additional mutations that cause cells in the tumor to progress to the cancerous stage.
The tumor is now malignant because the cancer cells have lost their normal growth regulation and are invasive and metastatic.
Invasive- they can migrate to other parts of the body.Metastatic- they can migrate to other parts of the body.
The final stage of cancer involves these cancerous cells spreading through the bloodstream or surrounding body fluids and establishing more tumors elsewhere.
If untreated, malignant cells will cause the death of the organism.
2 Categories of Gene
In some cases, a mutation causes a gene to be overactive. This overactivite contributes to the uncontrolled cell growth that is observed in cancer cells.
This overactivity contributes to the uncontrolled cell growth that is observed in cancer cells. This type of mutant gene is called an oncogene.
Tumor-Suppressor Gene- is normal, it encodes a protein that prevents cancer.
Oncogenes are the result of mutations that cause overactivity, while loss-of-function mutations in tumor-suppressor genes promote cancer.
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