The key difference between mRNA and tRNA is that the mRNA carries the genetic information of a gene to produce a protein while the tRNA recognizes the three nucleotide mRNA sequences or codons and carries amino acids to ribosomes according to the codons of the mRNA.
Nucleic acids such as DNA and RNA are macromolecules composing of nucleotides. Deoxyribonucleic Acid (DNA) is responsible for carrying genetic information from generation to generation while Ribonucleic Acid (RNA) involves mainly in protein synthesis. Although DNA is the main genetic material for most living organisms, some viruses have RNA genomes. Ribonucleotides are the monomers of RNA. Ribonucleotide has a ribose sugar, nitrogenous base and a phosphate group. Nitrogenous bases are two types such as purines and pyrimidines. The purines bases are Adenine (A) and Guanine (G), while pyrimidines are Cytosine (C) and Uracil (U). Generally, RNA is present in the cytoplasm. There are three classes of RNA: messenger RNA (mRNA), transfer RNA (tRNA) and ribosomal RNA (rRNA) and these three classes perform cooperative functions in protein synthesis.
CONTENTS
1. Overview and Key Difference
2. What is mRNA
3. What is tRNA
4. Similarities Between mRNA and tRNA
5. Side by Side Comparison – mRNA vs tRNA in Tabular Form
6. Summary
What is mRNA?
Messenger RNA (mRNA) is one of the three types of RNA that carries genetic information encoded in a gene to produce a protein. Hence, the mRNA sequence is similar to the coding sequence of the gene. During the gene expression, a gene undergoes transcription and results in an mRNA molecule. During the second step of gene expression; in translation, mRNA is read as the triplet codons. The genetic code of DNA specifies the amino acid correspondent to each of the triplet codons. In eukaryotes, a single mRNA is coded for a single polypeptide chain while, in prokaryotes, several polypeptide chains may be coded from a single mRNA strand.
Figure 01: mRNA
Most mRNA molecules have a short life span and high turnover rate. So they can be synthesized over and over again from the same stretch of template DNA. In this short lifetime, it is processed, edited and transported before the translation in eukaryotes. During the processing, several things occur such as 5′ cap addition, splicing, editing, and polyadenylation. In prokaryotes, processing does not occur.
In eukaryotes, translation and transcription occur in different places, so they need to be transported extensively. Hence, mRNA molecule travels from the nucleus to the cytoplasm.
What is tRNA?
The main function of transfer RNA or tRNA is to carry amino acids to the ribosomes and interact with the mRNA in the translation of protein synthesis. These tRNAs have 70-90 nucleotides. All matured tRNA molecules have a secondary structure containing several hairpin loops. In the end, the tRNA has anticodon which binds with mRNA.
Figure 02: tRNA
According to the order of the amino acids mentioned in the mRNA sequence, amino acids join with each other in an orderly manner. There is at least one type of tRNA for each amino acid. Because of that, a cell has large amount of tRNA. These tRNAs are synthesized in a precursor both eukaryotic and prokaryotic cells. The tRNA processing involves removal of short leader sequence from 5′ end, the addition of CCA instead of two nucleotides at 3′ end, chemical modification of certain bases and excision of an intron.
What are the Similarities Between mRNA and tRNA?
- mRNA and tRNA are two types of RNA present in living organisms.
- Both are essential for the protein synthesis of a cell.
- Also, both are polymers of ribonucleotides.
- And, both are single-stranded.
- Furthermore, they are in the cytoplasm.
- Besides, though they perform differently, they have cooperative functions in protein synthesis.
What is the Difference Between mRNA and tRNA?
As a result of gene expression, mRNA is derived from a DNA template. Hence, it carries genetic information of gene to produce a protein. On the other hand, tRNA is important in bringing amino acids to the ribosome according to the codons specified in the mRNA sequence. Thus, the key difference between mRNA and tRNA is the above-mentioned function of each molecule. Furthermore, there is a structural difference between mRNA and tRNA. mRNA is an unfolded linear molecule while tRNA is a 3-D structure composed of several hairpin loops.
Moreover, mRNA has codons while tRNA has anticodons. We can consider this also as a difference between mRNA and tRNA. Also, mRNA sequence length depends on the gene sequence while tRNA rages the length between 76 to 90. Hence this is also a difference between mRNA and tRNA. Generally, a cell has a large amount of tRNA than the mRNA.
The below infographic illustrates more facts on the difference between mRNA and tRNA.
Summary – mRNA vs tRNA
Among the three types of RNA, mRNA and tRNA are two types. Both are essential for the protein synthesis in a cell. However, the key difference between mRNA and tRNA is their function. mRNA carries the genetic information of a gene to produce a protein in three letter code while the tRNA brings amino acids to ribosome according to the codons specified in the mRNA sequence. mRNA is synthesized in the nucleus and transported to the cytoplasm. On the other hand, tRNA is present in the cytoplasm. mRNA a tRNA work cooperatively during the synthesizing polypeptide chain in the ribosome. Thus, this summarizes the difference between mRNA and tRNA.
Reference:
1. Nature News, Nature Publishing Group. Available here
2. “Messenger RNA.” Wikipedia, Wikimedia Foundation, 2 Jan. 2019. Available here
Image Courtesy:
1.”MRNA-interaction”By Sverdrup at English Wikipedia. (Public Domain) via Commons Wikimedia
2.”Peptide syn”By Boumphreyfr – Own work, (CC BY-SA 3.0) via Commons Wikimedia