Energy landscape theory and the funnel concept have enormously advanced our understanding of protein folding and more recently the role of global motions in protein function. Going beyond folding small and mid size proteins, the power of reduced models to study the physics of protein assembly, protein binding and recognition, and larger biomolecular machines has also proven impressive. Since energetic frustration is sufficiently small, native structure-based models, which correspond to perfectly unfrustrated energy landscapes, have shown to be a powerful approach to explore larger proteins and protein complexes, not only folding but also function associated to large conformational motions. Therefore a discussion of how global motions control the mechanistic processes in the ribosome and molecular motors will be presented. In this presentation we will focus on how the combination of detailed atomistic simulations and simplified structure-base models has allowed us to explore the entire landscape for the Ribosome. This would be impossible with one of these techniques alone. The effect of magnesium in controlling structure transitions will also be discussed mostly in the context of riboswitches.