Question

Polycistronic mRNA is characteristic of

• A. Prokaryotes
• B. Eukaryotes
• C. Both A and B
• D. Eukaryotes and viruses

Answer 1

The correct option is A Prokaryotes

Polycistronic mRNA molecule carries the coding region for several proteins and thus, is transcribed from more than one genes. These proteins function together in a biological process. They are present in bacteria. But monocistronic mRNA molecule encodes a single protein and thus, is transcribed from one gene. It is present in eukaryotes. A polycistronic mRNA has ribosome binding site near the start site for each of cistrons. Translation initiation can begin at any of these multiple internal sites, producing multiple proteins. Eukaryotic mRNAs have single initiation and termination sites and a single type of polypeptide is produced. Although polycistronic mRNA is characteristic of prokaryotes but they are present in Trypanosome and nematode and few insects (eukaryotes) also. The presence of polycistronic mRNA has been confirmed in RNA viruses also. Thus, the correct answer is option A.