The dense area within a cell that contains nucleic acids is known as the nucleolus. The nucleolus is responsible for assembling ribosomes, which are essential to protein production and organization in a cell.
The nucleolus is a structure within a cell's nucleus composed of the nucleic acid RNA as well as proteins necessary for the transcription of genetic information to new cells. A cell may contain several nucleoli, although the number is fixed depending on the type of organism. The nucleolus is protected by the nucleus itself, which is encased in a double layer of membrane that separates it from the cell's cytoplasm. The cytoplasm is a liquid inside a cell that contains its organelles and other components necessary for cell function.