And when proteins are embedded inside cell membranes, usually they act as transport proteins, and they allow the movement of different types of molecules and ions across the cell membrane of cells. Now, proteins are also involved in giving our cells structure. For example, the entire cytoskeleton structure consists of different types of proteins. Proteins also are involved in giving certain cells mobility. For example, sperm cells have a structure known as a Flagellum. And that flagellum is necessary to allow the sperm cell to actually move and navigate through the vaginal cavity and through the oviduct, the fallopian tube, in the female reproductive system.