Difference Between Polycistronic mRNA vs. Monocistronic mRNA

Main Difference

RNA stands for ribonucleic acid. There are three types of RNA present in cells; mRNA (messenger RNA), tRNA (transfer RNA, and rRNA (ribosomal RNA). mRNA is classified into two kinds on the basis of cells in which they are present and number protein codes, they are polycistronic mRNA vs. monocistronic mRNA. Polycistronic mRNA is that messenger RNA, which encodes for two or more proteins that are to be synthesized, and it is present in the translation in prokaryotic cells, whereas monocistronic mRNA is that messenger RNA, which encodes for only one or specific protein or polypeptide. It is present in the translation in eukaryotic cells.

Comparison Chart

Polycistronic mRNAMonocistronic mRNA
MessengerPolycistronic mRNA is that messenger RNA which encodes for two or more proteins.Monocistronic mRNA is that messenger RNA which encodes for only one or specific protein or polypeptide.
CodonsPolycistronic mRNA contains many codons of cistrons.Monocistronic mRNA contains single codon of cistron.
ORFPolycistronic mRNA have multiple ORFs (open reading frames).Monocistronic mRNA have single ORF (open reading frame).
Available inPolycistronic mRNA is present mostly in prokaryotes like bacteria etc.Monocistronic mRNA is present in eukaryotes like human cells.
Post-Transcriptional ChangesPolycistronic mRNA do not require post-transcriptional changes.Monocistronic mRNA requires post-transcriptional changes.

What is Polycistronic mRNA?

Poly means “many, ” and cistron means “genes.”An mRNA is said as polycistronic mRNA when it codes for two or many proteins; it contains more than one genes codes on it. Polycistronic mRNA contains many codons of cistrons. When it is transcribed in the cells, it has many codons that initiate this process and many codons that terminate them. The coding region that initiates the translation mostly consists of a linear structure or sequence of codons. These codons make it polyfunctional for the cell. Moreover, these RNA have multiple ORFs (open reading frames) each of which correspond to the single gene transcript. These codons or ORFs are then translated into a polypeptide according to the code. This mRNA is mostly present in the prokaryotes like bacteria etc. Many prokaryotic RNAs are completely functional and do not require any changes (post-transcriptional changes).

What is Monocistronic mRNA?

Mono means “one” and cistron means “genes.” An mRNA is said as monocistronic mRNA when it codes for only single proteins; it contains only one genes code on it. Monocistronic mRNA contains single codon of a cistron. When it is transcribed in the cell, it has only one codon that initiates this process and one codon that terminates them. The coding region that initiates the translation mostly consists of a linear structure or sequence of codons. These codons make it monofunctional for the cell. Moreover, these RNA has single ORF (open reading frame) each of which corresponds to a single or specific gene transcript. These codons or ORFs are then translated into a polypeptide according to the code. Monocistronic mRNA is present in eukaryotes like human cells. Many eukaryotic RNAs are non-functional and require many kinds of changes (post-transcriptional changes). These changes may be like splicing, splicing, removal of introns, etc.

Polycistronic mRNA vs. Monocistronic mRNA

  • Polycistronic mRNA is that messenger RNA which encodes for two or more proteins, whereas monocistronic mRNA is that messenger RNA which encodes for only one or specific protein or polypeptide.
  • Polycistronic mRNA contains many codons of cistrons whereas, monocistronic mRNA contains single codon of a cistron.
  • Polycistronic mRNA has many codons that initiate this process, and many codons that terminate them and counter to this monocistronic mRNA has only one codon that initiates this process and one codon that terminate them.
  • Polycistronic mRNA have multiple ORFs (open reading frames), whereas monocistronic mRNA have single ORF (open reading frame).
  • Polycistronic mRNA is present mostly in prokaryotes like bacteria while monocistronic mRNA is present in eukaryotes like human cells.
  • Polycistronic mRNA do not require post-transcriptional changes, whereas monocistronic mRNA requires post-transcriptional.

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