Answer to Question #137620 in Cell Biology for Lily

Question

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Bacteria are extremely efficient organisms. Which one of the following characteristics describes this efficiency in relation to protein production?
1)Bacteria are polycistronic and have multiple different genes on one mRNA.
2)Every gene is always turned on so that proteins are produced at a rapid rate.
3)Bacteria have multiple different types of polymerases for each gene.
4)Every gene has an activator that is necessary to begin translation so the cell doesn’t waste energy producing unnecessary proteins.

Answer 1

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. 

- 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.

*The presence of polycistronic mRNA has been confirmed in RNA viruses also.

[Monocistronic mRNA molecule encodes a single protein and thus, is transcribed from one gene. It is present in eukaryotes.

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 in few insects (eukaryotes) also.]