11.2.The nuclear envelope ( NE) The nuclear envelope is a complex structure instead of a simple nuclear membrane concept as a nucleus boundary and barrier The ne allows selective communication between the cytoplasm and nucleus, consequentially, a distinctive biochemical environment is established within the nucleus and is able to control access to chromatin, which has many advantages for regulation of gene expression and dna replication The ne contains several components
11.2. The nuclear envelope (NE) The nuclear envelope is a complex structure instead of a simple nuclear membrane concept as a nucleus’s boundary and barrier. The NE allows selective communication between the cytoplasm and nucleus, consequentially, a distinctive biochemical environment is established within the nucleus and is able to control access to chromatin, which has many advantages for regulation of gene expression and DNA replication. The NE contains several components:
1. Nuclear membrane, the core of the nuclear envelope It consists of two cellular membranes called the inner nuclear membrane: and outer nuclear membrane, arranged parallel and separated to each another The outer nuclear membrane is directly continuous with the er and associated with enzymes characteristic of the ER and studded with ribosomes on its cytoplasmic surface so it is functionally similar to the rer The inner surface of the inner nuclear membrane is bound to a dense filamentous nuclear lamina meshwork Two nuclear membrane at as a barrier that separates the contents of the nucleus from the cytoplasm. Other molecules except small nonpolar molecules are unable to diffuse through both them, as lipid bilayer membranes
1. Nuclear membrane, the core of the nuclear envelope It consists of two cellular membranes , called the inner nuclear membrane and outer nuclear membrane, arranged parallel and separated to each another. The outer nuclear membrane is directly continuous with the ER and associated with enzymes characteristic of the ER and studded with ribosomes on its cytoplasmic surface, so it is functionally similar to the RER. The inner surface of the inner nuclear membrane is bound to a dense filamentous nuclear lamina meshwork. Two nuclear membrane at as a barrier that separates the contents of the nucleus from the cytoplasm. Other molecules except small nonpolar molecules are unable to diffuse through both them, as lipid bilayer membranes
2. Intermembrane space( perinuclear space) The Intermembrane space is one by that two nuclear membranes are separated with 10-50 nm distance. The perinuclear space is directly connected with the lumen of the er. The perinuclear space is as a functionally physiological buffer zone. The perinuclear space is sensitive to pathological changes of the cell 3. Nuclear pore complex (NPC) The inner and outer nuclear membrane are joined at sites forming circle pores, called the nuclear pore complex(nPC). The average mammalian cell contains approximately 3000 nuclear pores. (see the next section)
2. Intermembrane space ( perinuclear space) The Intermembrane space is one by that two nuclear membranes are separated with 10-50 nm distance. The perinuclear space is directly connected with the lumen of the ER. The perinuclear space is as a functionally physiological buffer zone.The perinuclear space is sensitive to pathological changes of the cell. 3.Nuclear pore complex (NPC) The inner and outer nuclear membrane are joined at sites forming circle pores, called the nuclear pore complex (NPC). The average mammalian cell contains approximately 3000 nuclear pores.(see the next section)
Cytoplas Integral prote Outer membrane Ribosome inner membr Nuclear pore compl ER Intermembrane Lamina space Heterochromatin NPC.NM.so HC (b) 0.2 Figure 12.2 The nuclear envelope. (a) Schematic diagram showing the double membrane, nuclear pore complex, nuclear
rimately 560,000 ribosomal proteins and export ap- mately 14,000 ribosomal subunits every minute colloidal gold Nucleus 3,N , ribosome subunits Ah 0.1 um Figure 12.a The movement of materials through the nu