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Question: Why is radiation dangerous for cells?
Radiation is composed of high-energy waves or particles that can damage cells. The waves are things like X-rays and g (gamma) rays which are like visible light, but have a much smaller wavelength and thus higher energy. The particles can be electrons, which are part of atoms in substances. Radiation can be emitted from radioactive substances that can occur naturally in our environment or come from the sun or come from outer space in which case they are called cosmic rays.
When these energetic waves or particles hit living cells they can damage some of the components. They can interact with chemicals and chemical bonds between atoms and cause them to break due to the additional energy that radiation contains. Some of the chemicals are things like proteins, sugars or fats, which our cells can make more of if they are damaged. But the cell also contains DNA which is the blueprint of our cells, providing the information for making all the proteins, sugars and fats. If the DNA gets damaged, it can disrupt the information that is needed to make these cell components and thus disrupt the cell's ability to function. Imagine the challenge of an architect reading a blueprint that has a mistake on it. That person might make a building with only three walls instead of the normal four, and that wouldn't function as a house as well.
The cell does have a means for repairing DNA but sometimes that repair process is disrupted or doesn't occur correctly and the change in the DNA is permanent. If this change is in an important region of the DNA, a gene that for instance makes a protein that normally prevents the cell from dividing before it is supposed to, then that normal control process could be disrupted. Cells that continue to divide or grow even when they normally would not can lead to the family of diseases called which is often seen as one of the results of excessive exposure to radiation. We are naturally exposed to various types of radiation, like when you get your teeth or chest X-rayed or when you are out in the sun a lot. But we try to limit the exposure to a minimum or add extra protection to our body (like sunscreen) to protect the cells from getting too much exposure to radiation or a lead apron when we are getting our teeth x-rayed. In this way, we minimize the damage that radiation can cause while still getting the medical or physical benefits.
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