Final answer:
The statement is false; a polyribosome consists of multiple ribosomes translating a single mRNA molecule simultaneously, not a single ribosome translating many mRNAs. This complex process efficiently increases protein production within the cell.
Step-by-step explanation:
The statement 'A polyribosome is a single ribosome that is translating many mRNAs at one time' is false. A polyribosome, also known as a polysome, refers to a structure that includes multiple ribosomes simultaneously translating a single mRNA strand. This setup allows for the rapid and efficient synthesis of protein, as each ribosome moves along the mRNA, reading from 5' to 3' and synthesizing the corresponding polypeptide from the N terminus to the C terminus. The presence of multiple ribosomes on a single transcript vastly increases protein production, since each ribosome can independently assemble an identical protein.
In bacteria, transcription and translation are coupled, allowing ribosomes to begin translating the mRNA before transcription has even finished. This is in contrast to eukaryotic cells, where the mRNA must first be processed and transported out of the nucleus before it can be translated. This can lead to numerous ribosomes bound to a single mRNA, forming a polyribosome. In this way, a specific protein can accumulate rapidly within the cell.