Meaning of Carioteca
One of the fundamental components of the nucleus of eukaryotic cells is the karyotheca, also known as the nuclear envelope, nuclear envelope, nuclear envelope, or even karyomembrane.
It is a complex structure, consisting of two juxtaposed lipoprotein membranes and internally lined by a layer of protein filaments.
The outermost membrane of the cariotheca is continuous with the membranes of the endoplasmic reticulum and has ribosomes attached to the surface in contact with the cytoplasm.
The innermost membrane of the Carioteca has a slightly different chemical composition than the outer membrane. At certain points in the Carioteca, the two membranes merge into pores, through which substances are exchanged between the nucleus and the cytoplasm.
Between the two membranes, there is a short space called the perinuclear cavity.
Inside, the nuclear lamina, made up of a network of protein filaments about 10 nm thick, is attached to the karyotheca, whose function is to support and maintain the shape of the nuclear envelope.
During cell division, the carioteca disintegrates and the proteins that make up the nuclear layer become phosphorylated; at the end of the process (telophase), it forms again into the resulting nuclei.
The Carioteca allows the nuclear content to be chemically differentiated from the cytoplasmic environment, so that only the smallest apolar molecules have free passage, by diffusion, through the lipoprotein membranes of the Carioteca.
Larger substances such as proteins, RNAs, and polar molecules can only enter or leave the nucleus through nuclear pores.
In each nuclear pore there is a type of valve called a pore complex, a protein structure that opens allowing the passage of some molecules (especially those soluble in water) and then closes.
It is estimated that there are around 2000 nuclear pores in the karyotheca of a vertebrate cell, however, this number can vary depending on the function of the cell.
The term nuclear membrane is commonly used when referring to the Carioteca. However, this term is not appropriate, since the Carioteca is composed of two membranes and not just one.