In imagining the evolution of ATP synthase as a key component of the chloroplast endosymbiont, describe when you think the key elements proposed in lecture and your book must have been working during the process of creating a functional endosymbiont. Were the evolution of the two kinds of proton pumps a necessary precondition? Give three other changes in the chloroplast that might have contributed to the productive symbiotic relationship between the host and the chloroplast.