Practice Problems for Molecular Biology, Session 2: DNA Replication Question 1 ATP ? a) Box the part that is added to a growing chain of nucleic acid. b) Star the atom(s) that can form a hydrogen bond with the complementary nitrogenous base. c) Circle the part of the molecule that decreases the stability of RNA as compared to DNA. d) Draw an arrow to the part of this molecule that you would modify to prevent further elongation. Indicate what change you would make next to the arrow drawn. Question 2 Consider the following origin of replication that is found on a chromosome. The sequence of region 1 is shown. Region 1: 5??CTGACTGACA?3?