As discussed in the previous blogs, DNA is the key source for all the essential processes like Translation, Transcription, and Replication. This complete study of central dogma is solely known as gene expression. To study any kind of gene, it is important to know how it expresses.
Previously we synthesized DNA from DNA in replication, RNA from DNA in transcription. And now, we will study about what is the exact application of RNA synthesis. DNA is already present in our body then,
What is the need for RNA synthesis?
Why is RNA so important?
What is the use of transcript?
So, one answer for all the questions is the PROTEIN. The human body is full of mysteries; it needs nutrition, modifications, synthesis, breakdown, and many other things. To fully feel all needs, it regulates all the essential mechanisms by itself. Translation is one of the processes followed to fully feel the need for proteins in our body.
The process of RNA to protein synthesis is named Translation. Transcription is the source of this RNA. Every synthesized RNA is committed to its desired function; unlike rRNA, t-RNA, only m-RNA is committed towards protein synthesis. t-RNA has the commitment of transferring the molecules while rRNA is working as ribosomal RNA. Both t-RNA and rRNA helps in the translation process.
Where does RNA Translation occur?
Prokaryotes show a kind of easy picture for the Translation compared to eukaryotes because it occurs in cytosol due to lack of nucleus. While for eukaryotes, it is quite lengthy as it occurs in the cytoplasm (in ribosomes) due to a nucleus.
We had a discussion about specific conserved sequences for the transcription. Similarly, there are specific conserved sequences for the RNA Translation process. And these sequences provide a binding site for the particular molecule to initiate protein synthesis. Those sequences are the Kozak sequence in prokaryotes and the Shine-Dalgarno sequence in eukaryotes. The need for transcription is to synthesize the required protein for the body. Sequences between the start point and the endpoint are the part that gets translated is an open reading frame (ORF).
Splicing for Translation
Whenever the transcription occurs, it forms RNA with introns and exons. Exon is the coding region, and the intron is the non-coding region. Thus, in transcription, the first transcript form is hnRNA that contains both coding and non-coding regions. Before Translation, the RNA must go through splicing, that is, removing the non-coding region. This process of splicing is required to synthesize a complete coding sequence which will be further used for the translation process. An alternate type of splicing is the most common type in eukaryotes among all splicing methods.
Ribosomes
Most fundamental unit for RNA Translation and protein synthesis. Two common types of know ribosomes are the 70S in prokaryotes and 80S in eukaryotes. These ribosomes are divided into two subunits, namely Large Subunit and Small Subunit. Basically, the Ribosome is the protein synthesis factory.
Eukaryotes (the 80S) – Large Subunit (60S) Small Subunit (40S)
Prokaryotes (the 70S) – Large Subunit (50S) Small Subunit (30S)
You might be thinking 80 is not the summation of 60 and 40 neither 70 is of 50 and 30. So, ‘S’ is the sedimentation coefficient based on the rate of sedimentation of the units of ribosomes and not the summation. Ribosomes that work in Translation are the free ribosomes roaming in the cytoplasm until they don’t get mRNA to translate. The ribosomes bound on the endoplasmic reticulum can also take part in Translation.
Translation of mRNA
There are many questions about RNA translation like
What are the RNA translation steps?
What are the RNA translation tools?
So here we go in the detailed discussion about it.
Transcription synthesizes mRNA that is messenger RNA and is full of messages in the form of codons. The Translation is the process of decoding codes present on m-RNA in the form of proteins. After finishing the transcription of DNA to RNA in the nucleus, Translation begins outside the nucleus with the Ribosome to synthesize the protein.
Protein is a sequence of amino acids attached through the peptide bonds and is an essential nutrient for the body. It provides energy fuel for various body functions. These proteins get collected by the t-RNA one by one in the Ribosome for Translation. It’s like tying flowers one by one in a single thread to form a wreath.
There are three steps in Translation like transcription, namely Initiation, Elongation, and Termination.
Initiation –
Here, a small ribosome subunit first binds on the ribosome binding site present on the mRNA. This binding recruits all the essential enzymes and initiation factors. And starts the process from the start codon. Then t-RNA brings the first amino acid and binds on the start codon of mRNA sequence through its anticodon loop. Start codon sequence is always AUG (adenine-uracil-guanine) for all mRNA molecules and codes for methionine. After all this set of tools, the large subunit comes and binds on the small subunit and completes the initiation complex’s ribosome assembly.
Elongation –
in this step, the initiation complex ribosome continues to translate each codon, and tRNA continues adding amino acids one by one. As amino acids continue binding, the length of the amino acid chain gets increases. Amino acid binds together and form peptide bonds. Elongation is continuous till the reach of the stop codon.
Termination –
when the Ribosome reaches the stop codon, termination occurs after decoding the complete mRNA sequence. The newly synthesized protein is then released into the cytoplasm to perform the committed work. This protein can get released and stored into the endoplasmic reticulum (ER) too. And this stored protein is get further transported through vesicles to the target site when required.
One more thing I would like to add is Translation RNA is always mRNA
Summing up the complete story, m-RNA is like a reference book that contains lots of information, t-RNA is like writers of Mundus who choose the perfect pages to read, and Ribosome is worked as mundus2035 that provide the complete decoded information in simplest form. Also, our readers are like proteins that become committed to their targets after reading from mundus2035.
So, stay connected with us.
