Difference Between rRNA and mRNA

The key difference between rRNA and mRNA is that the rRNA is important to produce ribosomal proteins that catalyze the assembly of amino acids into protein chains while the mRNA is important to carry the genetic information coded in DNA to produce a specific protein in three letter genetic code.

Nucleic acids are the operators of life that can control almost every action related to life. There are two main types of nucleic acids such as DNA (Deoxyribose Nucleic Acid) and RNA (Ribose Nucleic Acid). DNA occurs as one type while RNA occurs as three main types namely messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA) based on their function and place of occurrence. All three types of RNA are present in both prokaryotes and eukaryotes and are extremely important in protein synthesis since they are essential to assemble the correct order of amino acids as encoded in DNA. All three types of RNA work differently, but fulfil cooperative functions in protein synthesis. This article intends to explore the characteristics of both rRNA and mRNA while highlighting the difference between rRNA and mRNA.

CONTENTS

1. Overview and Key Difference
2. What is rRNA
3. What is mRNA
4. Similarities Between rRNA and mRNA
5. Side by Side Comparison – rRNA vs mRNA in Tabular Form
6. Summary

What is rRNA?

Ribosomal RNA or rRNA, as the name implies, is always connected with ribosomes which are the sites of protein synthesis or translation in cells. In other words, rRNA is the RNA component of a ribosome. The basic function of rRNA associates with the protein synthesis inside a cell. Accordingly, rRNA governs the decoding of messenger RNA into amino acids, as it provides the mechanism.

Also, rRNA interacts with transfer RNA during translation, which is the conversion of a base sequence of nucleic acid (nucleotide sequence) into a protein molecule. The two subunits of ribosomal RNA are the large subunit (LSU) and the small subunit (SSU). During the protein synthesis, the small subunit reads the mRNA strand while the formation and progression of the protein molecule occur at the large subunit. However, it would be interesting to know that the messenger RNA strand progresses through the two subunits, often called sandwiched between SSU and LSU. Ribosome catalyzes the formation of a peptide bond in the protein molecule. Also, rRNAs being nucleic acids with nucleotide sequences, those could be regarded as reserves of genetic material.

What is mRNA?

Messenger RNA or mRNA is the transcribed copy of a gene. It carries the genetic information of a gene to produce a protein. In other words, it could be considered as the chemical blueprint of a protein. mRNA is single stranded. When a gene starts to express, it produces an mRNA sequence during the first stage of gene expression (transcription). It is complementary to template DNA strand but similar to the coding sequence.

Since mRNA carries information from DNA to form the protein, its function has been interested to be so named as messenger RNA. RNA polymerase enzyme breaks the hydrogen bonds at the desired place of the DNA strand and opens double helix structure to expose the nitrogenous base sequence. RNA polymerase arranges the corresponding ribonucleotides according to the exposed base sequence of the DNA strand.

Furthermore, RNA polymerase enzyme aids in forming the new strand by forming the sugar-phosphate bonds. After the formation of the mRNA strand, it provides information for protein synthesis in three letters codons, which are triplets of consecutive nitrogenous bases. These codons are read at ribosomal RNA, and the protein chains are formed using the sequence.

What are the Similarities Between rRNA and mRNA?

• rRNA and mRNA are two types of RNA.
• Both are important as they involve in protein synthesis.
• Also, both contain ribonucleotides.
• Besides, both are present in the cytoplasm of the cells.

What is the Difference Between rRNA and mRNA?

The mRNA carries information from DNA to ribosomes which are the sites for protein synthesis while rRNA facilitates the synthesis of protein. We can consider this as the key difference between rRNA and mRNA. Furthermore, mRNA formation occurs inside the nucleus while rRNA synthesis occurs in the nucleolus. Thus, it is also a difference between rRNA and mRNA.

Moreover, rRNA is attached to ribosomes while mRNA is not attached to ribosomes. Therefore, this feature also contributes to a difference between rRNA and mRNA. When considering the life span of each molecule, rRNA lasts longer than mRNA, as mRNA gets destroyed after providing the nucleotide sequence. Hence, life span is another difference between rRNA and mRNA.

Below infographic on the difference between rRNA and mRNA shows these differences as a side by side comparison.

Summary – rRNA vs mRNA

There are three types of RNA; mRNA, tRNA and rRNA. All three types involved in protein synthesis (translation). mRNA carries the three letter genetic code for the synthesis of a protein, while tRNA brings amino acids to the ribosome. rRNA links the amino acids in the correct order and assembles the polypeptide chain of the protein. Hence, all three types fulfil cooperate functions in protein synthesis. The key difference between rRNA and mRNA is the basic function of each molecule in protein synthesis. mRNA constitutes the genetic information of the protein while rRNA assembles the amino acids into a peptide chain. Furthermore, rRNA associates with the ribosomes while mRNA runs between two subunits of the ribosome during the protein synthesis. This is the summary of the difference between rRNA and mRNA.

Reference:

1. Lodish, Harvey. “The Three Roles of RNA in Protein Synthesis.” Current Neurology and Neuroscience Reports., U.S. National Library of Medicine, 1 Jan. 1970. Available here  

Image Courtesy:

1.”Ribosome mRNA translation en”By LadyofHats – Own work (Public Domain) via Commons Wikimedia 
2.”Pre-mRNA-1ysv-tubes”By Vossman – Own work, (CC BY-SA 3.0) via Commons Wikimedia