How do point mutations affect complementary base-pairing and widths of the nucleotide pairs?
When Point mutations occur in one strand of DNA, irregular base-pair emerge. One of the main features of this irregular state is that the width of the double-strand differs from the standard form(usually larger width as the new, irregular base pairings are weak) in that specific area. In other words, the portion of DNA which has the defective base-pair bulges out or protrudes leading to the asymmetry of DNA.(analogous but not the same as Thymine dimers) Most of the times the DNA repair system finds this and deals with it in the correct way. I do not know about the exact number of hydrogen bonds that appear in these situations but perhaps it obeys either Watson-Crick, Hoogsteen, or Wobble rules.