DNA Mutation Repair
Your body has many ways of fighting off DNA mutations in your body. Mutations are caused either by random chance, natural elements, or mutagens developed in the lab. Throughout our evolution our bodies have developed a very strong response to these mutations and ways to rid them from our cells.
UV radiation from the sun can cause pyrimidine dimmers to form in our dna structure. The UV radiation basically fuses to bases together which then leads to proteins being coded incorrectly and leads to things like cancers. Our body has developed a repair mechanism called damage reversal. When the mutation is very simple, our cells can just reverse the damage that happened. In the case of UV radiation, a repair enzyme called Photolyose splits the dimer in half, thus correcting the problem in our DNA.
Base excision repair is a more complicated process, but in the end does the same thing. This process is more mutations than are harder to get rid of. The process involves cleaving the backbone of the mutated base using DNA glycosylase. In the next step the enzyme AP endonuclease makes a cute in the backbone of the DNA and dRPase removes a large stretch of DNA. This insures that all mutated bases are removed from the DNA. Then the polymerase enzyme synthesizes new DNA using the template from the old DNA and the enzyme ligase seals the DNA closed. This process happens thousands of times a day in our body and is a very effective process. Through this process, 10^9 potentially dangerous errors are caught before they have a chance to hurt us.
Sometimes even base excision repair fails to catch a mutation, that’s where mismatch repair comes into play. The first step in this repair is to recognize the mismatches base pairs. This is usually easy to find by certain enzymes because there is usually a knick in the DNA strand caused by mismatched bases. Then an enzyme comes in and just removes the base and lets DNA continue to be synthesized. Sadly this system of repair isn’t perfect because if the chunk of effected DNA bases is too large it can cause for a crucial portion of the protein to not be translated and could end up still hurting us in the long run. When all of our repair mechanisms still don’t end up catching certain mutations, they end up causing things like cancers and tumors.