Final answer:
Polyribosomes, or polysomes, are structures where an mRNA molecule is translated by multiple ribosomes concurrently, increasing the efficiency of protein synthesis. Ribosomes consist of two subunits, which work together to translate mRNA into proteins. Polysomes are crucial in cells, allowing for rapid response in protein production.
Step-by-step explanation:
Polyribosomes, also known as polysomes, refer to a complex consisting of an mRNA molecule that is simultaneously translated by multiple ribosomes. This process occurs as ribosomes bind to the mRNA and systematically translate its sequence into a polypeptide chain. Multiple ribosomes can attach to the same mRNA, moving along it in a 5' to 3' direction, effectively increasing the efficiency of protein synthesis. These ribosomes are spaced closely together, forming what can visually appear as a 'string' of beads.
In eukaryotic cells, mRNA is transported out of the nucleus before being translated by polysomes. Due to the brief lifespan of mRNA, polysomes are crucial in maintaining a high rate of protein synthesis, enabling the cell to quickly respond to its protein production needs. When ribosomes reach the end of the mRNA strand, they disassemble and release the newly synthesized polypeptide.
The structure of the ribosome, which is essential for creating polysomes, consists of two differing subunits composed of ribosomal proteins and ribosomal RNA (rRNA). These subunits work together to translate the coded genetic information in the mRNA into amino acid sequences, thus forming proteins. Ribosomes, and in consequence polysomes, are abundant in all cells due to their key role in protein synthesis.