What are polyribosomes? Polyribosomes are clusters of ribosomes held together on an mRNA. Polyribosomes are clusters of ribosomal subunits held together as a single ribosome. Polyribosomes are clusters of mRNA held together by a single ribosome. Polyribosomes are clusters of proteins held together on an mRNA.
The Correct Answer and Explanation is:
Correct Answer:
Polyribosomes are clusters of ribosomes held together on an mRNA.
Explanation:
Polyribosomes, also known as polysomes, are structures formed when multiple ribosomes attach to a single molecule of messenger RNA (mRNA) simultaneously. This arrangement allows for the efficient synthesis of multiple copies of a protein from one mRNA strand at the same time, significantly increasing the cell’s capacity to produce proteins.
During the process of translation, a ribosome binds to an mRNA molecule and begins to synthesize a polypeptide chain by decoding the genetic information in the mRNA. As soon as the first ribosome moves far enough along the mRNA, another ribosome can bind to the start of the mRNA and begin translating. This leads to the formation of a polyribosome, where multiple ribosomes are spaced along a single mRNA, each independently synthesizing the same protein.
Polyribosomes are commonly found in both prokaryotic and eukaryotic cells. In prokaryotes, they often float freely in the cytoplasm, while in eukaryotes, they can be found free in the cytoplasm or attached to the rough endoplasmic reticulum. The presence of polyribosomes is an indicator of active protein synthesis and is crucial for rapid and high-yield production of proteins needed for various cellular functions.
It’s important to distinguish polyribosomes from other components of the protein synthesis machinery. They are not clusters of ribosomal subunits (which assemble into functional ribosomes), nor are they clusters of mRNA or proteins. Instead, they are functional complexes of full ribosomes translating a single mRNA. This setup exemplifies the efficiency of cellular machinery in optimizing gene expression and protein production.
