Читать книгу Cell Biology - Stephen R. Bolsover - Страница 38

The nucleus is often the most prominent cell organelle. It contains the genome, the cell's database, which is encoded in molecules of the nucleic acid, DNA. The nucleus is bounded by a nuclear envelope composed of two membranes separated by an intermembrane space (Figure 2.3). The inner membrane of the nuclear envelope is lined by the nuclear lamina, a meshwork of lamin proteins that provide rigidity to the nucleus and anchorage for the DNA. A two‐way traffic of proteins and nucleic acids between the nucleus and the cytoplasm passes through holes in the nuclear envelope called nuclear pores. The nucleus of a cell that is synthesizing proteins at a low level will have few nuclear pores. In cells that are undergoing active protein synthesis, however, virtually the whole nuclear surface is perforated.