How do the DNA bases fit together?
This problem is part of the Expt 1 problem set. Be sure to do it in lab and check your answer. 1.34 How does hydrogen bonding affect the thermal stability of DNA? Hydrogen bonds hold the DNA helix together. It takes energy to disrupt the H-bonds – added heat will provide enough energy to overcome the H-bond attraction between the DNA bases. The more H-bonds, the greater the thermal stability will be (the more heat required to disrupt the H-bonds). From Investigate This 1.33, we know that 3 H-bonds form per C-G pair and 2 H-bonds form per A-T pair. So if the C-G to A-T ratio is higher, thermal stability should be higher. 1.35-1.39 Sweating and energy diagrams. Your finger feels cooler when wet than when dry. This is because the water on your skin absorbs energy from your skin as it evaporates (goes from l to g phase). The energy change for the water as it is vaporized is + (endothermic, heat is absorbed). The energy change for the skin is negative (exothermic, heat leaves). For 1.39(a),
