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The mysterious cave of the nuclear envelope: why are nuclear pores so important?
In cell biology, the design and function of the nuclear membrane exhibit surprising complexity. The nuclear membrane, also known as the nuclear envelope, is a two-layer lipid bilayer structure surrounding the nucleus. In addition to providing protection for genetic data, it also plays a vital role in promoting the exchange of materials inside and outside the cell. With the deepening of research, these tiny "channels" of nuclear pores are considered to be a key component of the nuclear membrane that cannot be ignored.
Structure of the nuclear membrane
The nuclear membrane is composed of two lipid bilayers: the inner nuclear membrane and the outer nuclear membrane, and the space between these two membranes is called the "perinuclear space" and is usually between 10 and 50 nanometers wide. The outer nuclear membrane is connected to the inner nuclear membrane and remains connected to the membrane of the endoplasmic reticulum, which plays an important role in the regulation of cell functions.
There are a large number of nuclear pores in the nuclear membrane, which allow materials to pass freely between the cytoplasm and the nucleus. This is essential for the proper functioning of cells.
Function of nuclear pores
Nuclear pores are special structures on the nuclear membrane. There are usually about 1,000 nuclear pore complexes on each cell nucleus. These nuclear pores are about 100 nanometers in diameter, with internal channels about 40 nanometers wide. The existence of these structures allows various molecules and messages to be efficiently transported between the nucleus and cytoplasm.
The nuclear pore complex is composed of a variety of nucleoporins, which are responsible for connecting the inner and outer membranes and playing a central role in nuclear material transport.
Nuclear membrane during cell division
During the G2 phase of a cell, the surface area of the nuclear membrane increases significantly and the number of nuclear pores doubles. In different organisms, such as yeast, the nuclear membrane remains intact during closed mitosis, but in other eukaryotes such as animals and plants, the nuclear membrane must disintegrate in the early stages of mitosis to allow the spindle filaments to enter the nucleus. Access chromosomes.
Destruction and reconstruction of nuclear membrane
In mammals, the nuclear envelope rapidly disintegrates within minutes during the early stages of mitosis. This process involves multiple steps, including phosphorylation of nucleoporins and their selective removal. In addition, although the reconstruction process of the nuclear membrane is still controversial, there are two main theories: one is the "vesicle fusion" theory, and the other is the "endoplasmic reticulum remodeling" theory.
The "endoplasmic reticulum remodeling" theory holds that some parts of the endoplasmic reticulum re-cover the nuclear area after the nuclear membrane dissolves, thereby rebuilding a complete nuclear membrane.
The origin of the nuclear membrane
The origin of the nuclear membrane involves in part the study of evolutionary biology, and scientists have proposed a variety of theories, including that it may have originated from prokaryotic cell membrane invaginations, or that it was a truly new structure established in an early archaeal host. membrane system. The nuclear envelope may exist to protect the genome from reactive oxygen species (ROS) generated within the cell.
Conclusion
The study of the nuclear envelope and its nuclear pores not only reveals the complexity of embryonic development and cell function, but also helps to understand many mechanisms related to cellular diseases. However, researchers still have many unanswered questions about how the integrity of the nuclear membrane is protected and maintained amid dynamic changes in the cellular environment. In the future, how will the scientific community view the multiple functions of the nuclear membrane, which may become a hot topic of research?
