Induced mutations : Mutations can be induced by exposing organisms or cells to a variety of treatments. Some of the most common are:. Radiation - One of the first known mutagens, radiation is a potent inducer of mutations. Different types of radiation cause different types of genetic changes.
Ultraviolet UV radiation causes point mutations. X-rays can cause breaks in the DNA double-helix and lead to translocations, inversions and other types of chromosome damage.
Exposure to the UV rays in sunlight has been linked to skin cancer. Note that the DNA damaging properties of radiation have been utilized in several different radiation-based cancer treatments. Shown below is a type of mutation that is caused by ultraviolet radiation. In this example, the bombardment of the DNA double-helix by UV rays causes two bases to join together.
This alters the structure of the DNA and can lead to permanent changes if not repaired. Another type of radiation is the energy emitted by naturally occuring radioactive elements like radon and uranium or man-made sources like those found and created in nuclear reactors. Radiation of this type comes in different types and can cause different types of damage to cells and tissues.
Radiation can directly damage DNA or can cause the formation of chemicals i. Exposure to radiation from radioactive materials has been well documented. Analyses of survivors of the atomic bombs dropped on Japan during World War II showed large increases in leukemias shortly after the exposure and then increases in other cancer types over the following decades. Dangerous amounts of radioactive materials have also been accidentally released from nuclear power plants.
Radiation exposure due to the accidental release of radioactive materials from the Chernobyl nuclear reactor have been associated with increases in thyroid cancer and other malignant cancers. Medical imaging machinery like X-ray machines and CT scanners also expose patients to radiation. The amounts used for any single test are not thought to cause siginificant amounts of cancer, but the long term impact of many tests over a period of years is not clear.
Chemical mutagens - Many different chemicals are known to cause mutations. These chemicals exert their effect by binding to DNA or the building blocks of DNA and interfering with the replication or transcription processes.
Some examples of potent mutagens are benzo-a-pyrene, a chemical found in cigarette smoke, and aflatoxin, a mutagen most often found on improperly stored agricultural products. Chronic inflammation - Chronic inflammation can lead to DNA damage due to the production of mutagenic chemicals by the cells of the immune system. An example would be the long-term inflammation caused by infection with the hepatitis virus. Learn more about viruses and cancer. Oxygen Radicals - During the capture of energy from food, which occurs in our mitochondria , chemicals may be generated which are very reactive and are capable of damaging cell membranes and DNA itself.
These r eactive o xygen i ntermediates ROI may also be generated by exposure of cells to radiation, as shown below. The mutagenic activity of ROI is associated with the development of cancer as well as the activities of several anticancer treatments, including radiation and chemotherapy. During mitosis , it is possible that the cell division process fails to divide the replicated chromosomes accurately into two daughter cells. An error of this type will lead to the production of aneuploid cells.
The cells will either be missing, or have gained a significant number of genes. This rare process can create cells that are more prone to unregulated cell division. As stated previously, a large percentage of cancers isolated from humans are aneuploid. If a cell has a mutation in a gene whose protein product is responsible for 'checking' on the division process, things can rapidly get out of control and the daughter cells of each division can become increasingly abnormal.
Viruses are thought to be responsible for a significant percentage of cancer cases. Viruses can cause cancer in a variety of ways and the way that each type of virus works is likely to be slightly different. Some viruses including many retroviruses can cause mutations by inserting their genes into the genome of the infected cell. The inserted DNA can destroy or alter the activity of affected genes. Viruses can also cause mutations in indirect ways.
As an example: An infection with hepatitis virus can last for many years. During that time the body's defense system tries to get rid of the virus by producing toxic chemicals. Those chemicals can cause damage to otherwise healthy 'bystander' cells, sending them down the road that leads to cancer. There are numerous other ways that viruses can cause cancer.
Because of the importance of viruses in the development of many cancers we have created a section devoted to viruses and cancer. Transposons encode an enzyme , transposase, that acts to splice the transposon into new locations in a genome see schematic, below left, of a transposon Transposons were discovered by Barbara McClintock and she won a Nobel prize for her work.
Other leukemia and blood cancer-related symptoms that everyone should be aware of include:. Obtaining an accurate and timely diagnosis for blood cancer is the most important element to successful treatment and management of symptoms. The board-certified oncologist and leukemia specialists and the Cancer Center of Southern California offer individualized treatment and care for patients at all stages. Next, read Chronic Lymphocytic Leukemia.
All Rights Reserved. The information available on this web site is provided for informational purposes only. Learn about some of these blood disorders. Learn more on Blood disorders. Polycythemia vera. Polycythemia vera PV develops when the body makes too many red blood cells and sometimes too many white blood cells or platelets. Learn about PV. Learn more on Polycythemia vera. Idiopathic myelofibrosis. Learn about symptoms, diagnosis and treatment of IM.
Learn more on Idiopathic myelofibrosis. Essential thrombocytosis. Essential thrombocytosis ET develops when the body makes too many platelets. Learn about symptoms, diagnosis and treatment of ET. And some people can inherit faults in particular genes that make them more likely to develop a cancer. Some genes get damaged every day and cells are very good at repairing them. But over time, the damage may build up. And once cells start growing too fast, they are more likely to pick up further mutations and less likely to be able to repair the damaged genes.
Skip to main content. How cancer starts. This page tells you about how cancer starts. There is information about Cell changes and cancer. Manage your cookie settings here. Placeholder content. Last reviewed 1 July What is cancer?
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