There are numerous events that lead to DNA damage or at least a change in the original DNA sequence. These modifications may or may not have visible effects in the expressed product. However, these modifications may or may not be repaired by various DNA repair mechanisms available in living systems.
A. Deamination is simply the removal of an amine group from the molecule. In nitrogenous bases, deamination could lead to the formation and recognition as different base. Deamination of C, for example, would create uracil, which is not natural in DNA. In the given molecule, if the C at the bottom strand (7th base) is deaminated, the resulting daughter dsDNA would be:
Consider the following DNA sequence:
5' - TAAGCTGCTG - 3'
3' - ATTCGACGAC - 5'
A. Deamination occurs at the C at position 7 (bottom strand). Show the double-stranded DNA daughter sequences following a round of DNA synthesis.
B. What would happen if the original sequence were irradiated with UV?
C. What repair pathway would be used to repair the mutation in (A)?
D. What repair pathway would be used to repair the UV products in (B)?
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