The nucleolus (also called nucleole)'s a non-membrane bound structure composed of protein and nucleic acids found within the nucleus. The ribosomal RNA's transcribed within the nucleolus. The nucleolus ultrastructure can be visualized through an electron microscope, while the organization and dynamics can be studied through fluorescent protein tagging and fluorescent recovery after photobleaching (FRAP). Malfunction of nucleoli can be the cause for several human diseases. It's the main part of… (More on Nucleolus)