What is it?
Ionizing radiation can cause DNA damage in a variety of ways. The destructive effects of ionizing radiation can often be felt in living and non-living things. The DNA molecules are the most affected by radiation in living cells. Although it cannot be said that these DNA molecules are destroyed first by radiation, it is their damage which proves to be the most severe and irreparable. Radiation damage plays a secondary role in the destruction of various cytoplasmic structures within cells, such as mitochondria and lysosomes.
Let’s begin by understanding how radiation damages DNA. It is a double-stranded macromolecule that can be twisted helically and allows for storage, reading, and transmission of genetic data. It is composed of two chains that are connected to one another. Each of these chains is then formed by nucleotides, which are separate blocks. A nucleotide is composed of a nitrogenous bases, a sugar (deoxyribose) and a phosphate group. There are four types of nitrogenous bases in DNA. They are cytosine (thymine), guanine (guanine), and adenine.
Deoxyribose and the phosphate group are responsible for nucleotide chains. This is known as a phosphodiester bond. The complementarity (mutual correspondence between molecules) of nitrogenous base to each other using weak interactions – Hydrogen bonds: Adenine forms bonds only thymine and cytosine with the guanine. The adenine–thymine bond is less strong than the cytosine–guanine bond and requires less energy to break.
Two main ways that ionizing radiation can damage DNA cells are:
Ionizing radiation directly influences the breaking of phosphodiester bonds among nucleotides and chemical modification (damage to nitrogenous bases) as well as cross-linking of molecules. This causes single-stranded (one damaged strand), double-stranded breaks (both damaged strands), intra- and intermolecular crosses-links (different DNA DNA strands, nucleotides of each strand), DNA cross-links to chromatin, or nuclear matrix proteins to be formed in the molecule. Most damage, such as base modifications and single-strand break, can be handled by the cell easily. However, if the damage is severe or difficult to repair (e.g. double-strand breaks), the cell’s repair mechanisms may not be able to fix it.
Indirect effects from free radicals that arise from the ionization water in the cell, under the radiation. This can cause damage of 70 to 80%. Highly active free radicals can oxidize the nitrogenous bases of DNA, such as easily oxidized Guanine, and also break down bonds between nucleotides.
The cell will die if the critical mass of damage exceeds it. Because of the increased oxygen in cells, this causes even more oxidation of DNA molecules. For radiation with a high line energy transfer, alpha particles are often used. A simple hit to a cell can cause its death.
This is why science finds it so fascinating.
It is possible to create ways to protect healthy cells from radiation by studying the effects of ionizing radiation. Oncology is a case in point. There are ways to increase the radiation’s harmful effects on tumor cells.
What are you looking for?
Do I have to be concerned about fluorography? Which radiation doses pose a danger? What are the actual risks to human health from radiation exposure? These questions can be answered by understanding how ionizing radiation affects DNA in our cells.
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