So, for example, the rigid proteins might be involved in giving ourselves its structure, so they might be involved in creating the cyoskeleton, while the not so rigid proteins basically are involved in those processes that require a bit more flexibility. Now, proteins do not act by themselves or usually they don't act by themselves. Proteins usually interact with other proteins or other macromolecules to form these fully functional complexes. And these protein complexes are responsible for creating those different types of processes and reactions. So, for instance, when we study DNA replication, we'll see that a single protein is not actually involved in DNA replication. We have many, many different types of proteins that have to work together and form these protein complexes to actually carry out the process of synthesizing, replicating DNA molecules and DNA strands.