Messenger RNA or mRNA is also called messenger ribonucleic acid. This is a type of ribonucleic acid or RNA transcribed from a DNA (deoxyribonucleic acid ) template. One strand of mRNA consists of four different base types including uracil, cytosine, guanine and adenine. Ever one of these bases corresponds to an antisense DNA strand’s complementary base. Also, an organism’s genetic information is encoded into the mRNA, which you can learn more about in this Biology course.
mRNA is a large RNA molecule family which conveys genetic information to the ribosome from the DNA. In the ribosomes these specify the amino acid sequence of the gene expression protein products. Following transcriptions of primary transcript mRNS known as pre-mRNA, mature mRNA translates into an amino acid polymer.
Just like with DNA genetic information, mRNA genetic information is in the nucleotides sequence, arranged into a codon that has three bases each. Except for the stop codons, each codon encodes for a particular amino acid. Just as their name suggests, stop codons terminate the synthesis of protein.
To make new proteins that carry out the work of a cell, cells use genetic information that the mRNA contains. The cells translate the code which the mRNA contains into a new language based on amino acids, which happens to be the language of proteins. In protein-assembly, other RNA types like tRNA which stands for ‘transfer ribonucleic acid’ also assist the process.
The mRNA Sequence
The sequence of mRNA is transcribed from DNA, which carries information from the synthesis of protein. In mRNA, three consecutive nucleotides encode either a stop signal for protein synthesis or an amino acid. The trinucleotide is called a ‘codon.’
Here is a the relationship between a DNA sequence and an mRNA sequence, as well as the peptide encoded. The mRNA sequence complements the template strand of the DNA, and thus is the same as the coding of the DNA, except that ‘U’ replaces each ‘T,’ as you can see below:
With the sequence of mRNA, amino acids are then able to assemble into proteins. After mRNA becomes synthesized from a single DNA strand, it transfers out of the cell’s nucleus and into the cytoplasm. Within the cytoplasm, a ribosome moves along the strand of mRNA and reads the code A-U-C-G, three bases simultaneously. Each string of three bases is a code for specific amino acids. For instance, if the ribosome detects U-C-A, it then assembles serine, an amino acid onto the protein that is getting formed.
Down the RNA strand, the ribosome continues and reads the 3-base sequence. Once it reaches the mRNA strand’s end, the process if completed and there is then an available complete protein for the body to use.
Understanding the Sequence of mRNA
To understand the mRNA sequence, determine the base order that is in the sequence of DNA. Each of the bases has a pair base on the opposite strand of it. The four bases happen to be T for thymine, G for guanine, C for cytosine and A for adenine.
Find the DNA antisense strand through inserting the base pair that compliments each given base. Cytosine complements guanine and adenine complements thymine, for example. In other words, each time you see a ‘G,’ replace this with a C and each time you see a ‘C,’ replace this with a ‘G.’ The result is a complete DNA antisense strand or helix, which you can learn more about by taking this course entitled GCSE Biology: OCR B1.
Next, find the base mRNA pair through inserting the base RNA corresponding to the antisense DNA base helix you have found. Cytosine and guanine still complement each other. However, since the RUNA sugar unites are ribose rather than the deoxyribose of DNA, RNA won’t bind to the thymine nucleotide base. Rather, uracil is the complement of adenine, as this Basic Biology course shows you.
For an example of this process, here is a strand of DNA. It is then followed by a DNA antisense strand and finally by a strand of mRNA: AGACTTGCA->TCTGAACGT->AGACUUGCA
Messenger RNA and tRNA Synthesis
Both tRNA and mRNA go through transcription and base pairing which are processes for synthesis. In this process, a chain or RNA gets laid down beside a DNA strand. In archaea and bacteria, 2 of the 3 main divisions of earthly life, the synthesis of RNA takes place on 1 chromosome. In eukarya, the synthesis of RNA takes place inside the nucleus, where DNA is found in one or more chromosome. Both tRNA and mRNA contain information in the form of 4 of the possible base sequences in each nucleotide. In turn, the sequences go through synthesis based on the DNA nucleotide sequence. This happens in the gene or DNA which was utilized for synthesizing the strand of RNA during the process of base pairing.
Example of mRNA Sequencing
Question: If the sequence of DNA is ATGCGCAGTTATTGCGAT, what is the sequence of mRNA?
To answer this question, first you need to remember that the function of mRNA is for transcription. This means that it needs to duplicate the original message of the DNA which remains within the nucleus. Then, the RNA can take the DNA-transcribed message out of the cytoplasm and become attached to a ribosome where there can be a translation of the message and the construction of a protein. Note that RNA is different from DNA since it lacks the nitrogenous thymine base. Instead, it has a uracil base. Rules of base pairing are identical with the DNA, except that since RNA lacks thymine, there is a DNA base adenine. Instead, substituted the uracil base. Thus, UACGCGUCAAUAACGCUA would be the mRNA corresponding code to your sequence of DNA.
Practical Applications of mRNA Sequencing
Messenger RNA sequencing is necessary in the synthesis of protein, which is necessary for humans to live. Without the proteins being synthesized, normal functions such as breathing and energy expenditure would not be possible, as cells would be denied a vital source of energy.
Currently, mRNA is also being investigated to be potentially used in the prevention and treatment of diseases. Vaccines based on mRNA are being developed as prophylactic vaccines for infectious diseases and for cancer immunotherapy. Also, mRNA is being studied for protein replacement therapy in vivo and as a source of therapeutic gene products, which you will understand better once you take this A+ Biology course.