Cell nucleus
The nucleus is the largest cellular organelle in animal cells.
In mammalian cells, the average diameter of the nucleus is approximately 6 micrometres (µm), which occupies about 10% of the total cell volume. The viscous liquid within it is called nucleoplasm (or karyolymph), and is similar in composition to the cytosol found outside the nucleus. It appears as a dense, roughly spherical or irregular organelle. The composition by dry weight of the nucleus is approximately: DNA 9%, RNA 1%, Histone Protein 11%, Residual Protein 14%, Acidic Proteins 65%.
Yop1p
About half the total area of membrane in an eukaryotic cell encloses the space of the endoplasmic reticulum. The ER is an extremely dynamic membrane organelle which consists of the nuclear envelope and the peripheral ER. It is organized into a netlike labyrinth of branching tubules and flattened sheets that extends throughout the cytosol. These tubules and sheets are interconnected and their membrane is continuous with the outer nuclear membrane. The ER and nuclear membranes form a continuous layer enclosing a single internal space, called the ER lumen, which often occupies the 10% of the total cell volume. However, this unique space has several morphologically distinct areas. Thus, the peripheral ER is composed of a polygonal network of tubules and interdispersed sheets that spreads from the nuclear envelope to the cell cortex.