kärnporerna

Kärnporerna, or nuclear pores, are protein-lined channels that regulate the transport of molecules between the nucleus and the cytoplasm of eukaryotic cells. They are complex structures, forming a gateway through the nuclear envelope, a double membrane that surrounds the cell's nucleus. Each nuclear pore complex is composed of many different proteins called nucleoporins.

These pores are crucial for cellular function. They allow essential molecules like messenger RNA (mRNA) and ribosomal RNA (rRNA) to exit the nucleus and enter the cytoplasm, where they can be translated into proteins. Conversely, they permit proteins, such as transcription factors and enzymes needed for DNA replication and repair, to enter the nucleus from the cytoplasm.

While small molecules can pass through the nuclear pore by passive diffusion, larger molecules require active transport mediated by specific transport receptor proteins. This selective transport ensures that the nucleus maintains its distinct molecular environment, which is vital for gene expression and overall cellular regulation. The intricate structure and regulated function of nuclear pores are fundamental to life in eukaryotic cells.