After ionizing radiation treatment, a specific site in the human genome was foun

Question

After ionizing radiation treatment, a specific site in the human genome was found to have a damaged thymidine creating thymidine glycol. If working properly, what repair method will fix this type of damage (explain your reasoning)? If not excised in time, during replication, this type of damage will pair with guanine. What will the mutational event caused by this be? Write your answer in the form of XXXX (for example, ATTA; and show your work):

A rare methylated form of guanine pairs with thymine. If an O6-methylation of guanine occurs during replication in a GC pair, what will be the resulting mutant pair and mutational event (show your work)?

Explanation / Answer

Pyrimidine dimer causes conformational changes in the DNA structure which allows recognition of lesion. It is repaired by process of photoreactivation, in which enzyme photolyases directly reverse the process. Nucleotide excision repair mechanism is used to for repair of lesions such as Xeroderma pigmentosum (genetic disease).

incorporation of guanine during DNA replication causes a G:C base pair to be mutated to T:A. this all is due to base excision repair( removing damaged bases caused by mutation). BER gets activated by DNA glycosylases, which recognize and remove the inappropriate bases, which is cleaved by AP endonuclease.

If an O6-methylation of guanine occurs during replication in a GC pair, causing a G:C to A:T transition in DNA.

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