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%.
Nuclear envelope
The inner nuclear membrane encloses the nucleoplasm, and is covered by the nuclear lamina, a mesh of intermediate filaments which stabilizes the nuclear membrane as well as being involved in chromatin function and entire expression. It is connected to the outer membrane by nuclear pores which penetrate the membranes. While the two membranes and the endoplasmic reticulum are linked, proteins embedded in the membranes tend to stay put rather than dispersing across the continuum. It is lined with a fiber network called as nuclear lamina which is 10-40 nm thick and provide strength.