H-bonding Sites for DNA Base Pairs

[Emma Chang 1G]

I wasn't able to attend Dr. Lavelle's Zoom Review on Wednesday, and I was confused about the third slide from the bottom.

https://lavelle.chem.ucla.edu/wp-conten ... w_Zoom.pdf

I was wondering if anyone could tell me how we determine that there are eight H-bonding sites with H2O molecules for both adenine and thymine just by looking at the structure? Thank you!

[Catie Donohue 2K]

Each N atom has a lone pair, which can act as a site for hydrogen bonding if another H attaches there. Additionally, each H can attach to a nitrogen, oxygen, or fluorine on another compound to form an H bond. This is what I understood from it - feel free to correct me or add anything. Hope it helps!