Chemical Structure and Hydrogen Bonds in Base Pairs

Draw the chemical structure of a correctly base paired G-C pair, then re-draw the pair with a propeller twist (these answers should all be on one page following box 'G'). Identify which hydrogen bonds are strengthened, weakened or left unchanged and why. Repeat the process for a base pair buckle and base opening. In this specific case, to simplify the answer, do NOT allow rotation of any amino groups on the bases - keep every structural feature fixed EXCEPT the twist, buckle or opening action.