Microbiology Day 15 - Mircrobiology Day 15 Its more like a...

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Mircrobiology Day 15 It’s more like a gene conversion, where it’s a single strand bind converted. In single strand conversion, one of them will be degraded and copied but in double strand, it doesn’t happen DNA repair is kind of the same as gene conversion. In the video of base excision repair. This is occurring in all of us. In this case, the example is a cytosine being deaminated and on the figure, we can see what happened. It’s a common chemical reaction and is in uracil. The options for this are to repair it before replication, or replication before repair. What’s the difference between both options? If it’s repaired after replication, you will get a mutation. If it’s repaired before, you get no mutation. This can happen spontaneously and it’s not a mutation unless it gets replicated and inherited. Uracil can get incorporated and used by DNA polymerase equally to dTTP as a monomer for DNA replication, so uracils can be misincorporated. So DNA won’t recognize difference between T and U so pools of DUTP are kept low. Deoxyuracil was used in normal metabolic functioning to make thymine. So uracil is made first before thymine in normal mechanisms. So pools of uracil can build up but other enzymes keep it low. Example is dUTPase which takes dUTP and converts it to dUMP which can be used for something else. What’s the consequence for inhibiting dUTPase? It would inhibit production of thymidine and this is used in theurapeutic drugs. So if I block thymidine by folate acid and another way. You can also get thymidine through salvage pathway. So dUTP can be used by DNA polymerase equally to dTTP so two different ways of getting uracil in through spontaneous deamination and misincorporation and in both cases, they have to be removed. Enzyme called HTGP that’s important in making nucleotides and if not working, can lead to autoimmune diseases. (CHECK). This is something that happens naturally and this is the result of a mutagen. We see a specifc base being removed by a specific repair enzyme. So glycosylases remove a specific base, leading to an AP site (Amines without a purine or apurinic site or apyrimidinic). What’s first thing enzyme would recognize? It would recognize a bulge since they don’t pair and then they would match mismatch. They then recognize the structure. If this was spontaneous deaminated C, would it be a mismatch with U and G, so you don’t see a G. What if it was a uracil that was misinserted? It would be A and it would be harder to recognize. Sometimes they can recognize change, and it’s usually secondary site.
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