9 Reasons Why RNA Is So Important To Life On Earth

RNA stands for Ribonucleic Acid. It is a complex organic substance present in living cells whose molecules consist of many nucleotides linked in a long chain.

RNA is a naturally occurring chemical compounds that serve as the primary information-carrying molecules in cells. It’s formed from a section of DNA to further run the gene expression mechanisms.

Well! That’s not all. There are so many importance of RNA that will make you feel that without RNA life isn’t really possible to exist.

Before all let’s introduce a bit about RNA and its structure. So, let’s get started…

---

What’s RNA and its structure

RNA is one of the very important organic molecules in genetic, next after DNA.

RNA (Ribonucleic acid) is a nucleic acid present in all living cells and its principal role is to act as a messenger carrying instructions from DNA for controlling the synthesis of proteins.

It is important to note that in living organisms, DNA is the prime storehouse of genetic information, and RNA is formed from that DNA whenever the need for the formation of proteins arises.

Although in some viruses (like retrovirus), RNA rather than DNA carries genetic information.

In these non-living viruses, RNA is present which replicates, stores genetic information, and only gets expressed as (DNA → mRNA → Protein) if the virus enters a living host cell.

RNA is a polymer of nucleotide. Each RNA nucleotide is formed of:

1. Ribose Pentose Sugar
2. Phosphate Group
3. One of any four Nitrogenous bases: Adenine(A), Guanine(G), Cytosine(C), and Uracil(U)

RNA has Uracil instead of Thymine. The other three N-bases viz. Adenine, Guanine, and Cytosine are the same as in the case of DNA.

Uracil (U) base is also a pyrimidine and is very similar to that of DNA’s thymine (T).

Now, let’s know about the importance of RNA. There are 9 important reasons to consider. Let’s know about these.

---

9 Reasons Why RNA Is So Important To Life On Earth

1. The primary role of RNA is to convert the information stored in DNA into proteins

We all have studied the Central Dogma Model of Biology, right?

This model indicates the primary two-step process properly viz. transcription and translation, by which the information in genes flows into proteins: (DNA → RNA → Protein).

According to this Central Dogma theory, it’s indicated that the primary role of RNA is to convert the information stored in DNA into proteins.

How? The Central Dogma Model shows the basic framework showcasing the flow of genetic information from DNA sequence to the proteins thus bringing adequate changes to the living body.

DNA as the genetic information storehouse is very stable and so cannot be broken down so easily. That DNA replicates first to form multiple copies.

The non-template (coding) DNA strand acts to facilitate proper transcription to mRNA from the DNA. Messenger RNA (mRNA) carries the genetic information copied from DNA and translates it to proteins.

For proper protein synthesis, messenger RNA must be made from one strand of DNA called the template strand. The other strand, called the coding strand, matches the messenger RNA in sequence except for its use of uracil in place of thymine.

2. mRNA (messenger RNA) helps in encoding the amino acid sequence of a polypeptide

During Transcription, the information in a strand of DNA is copied into a new strand of messenger RNA (mRNA).

mRNA is a very simple single-stranded RNA molecule that is complementary to one of the DNA strands of a gene. It’s highly involved in the creation of proteins.

The difference between the DNA and mRNA here is that DNA stores the genetic information in an encrypted form whereas, mRNA decrypts the same information and makes it easy to encode proteins.

A peptide is a compound consisting of two or more amino acids linked in a chain. And a polypeptide is a linear organic polymer consisting of a large number of amino-acid residues bonded together in a chain, forming a protein molecule.

So, mRNA (messenger RNA) helps in encoding the amino acid sequence of a polypeptide by reading each codon on the mRNA structure.

Each codon consists of three nucleotides present in part of mRNA, usually corresponding to a single amino acid.

For example, the codon CAG represents the amino acid Glutamine.

3. tRNA (transfer RNA) brings amino acids to ribosomes during translation

Molecules of tRNA are responsible for matching amino acids with the appropriate codons in mRNA. This results in the creation of proteins.

The tRNA functions as the transfer vehicle which is very important for the flow of genetic information from mRNA to Protein.

mRNA simply cannot directly form the proteins. It is dependent on tRNA and ribosomes to form proteins.

During the time of translation (protein synthesis) from mRNA to proteins, the tRNA reads the mRNA based on a particular sequence of three nucleotides (codons).

When a tRNA recognizes and binds to its corresponding codon along with the ribosome in the mRNA strand, the tRNA transfers the appropriate amino acid to the end of the growing amino acid chain.

This leads to the formation of protein polypeptide chain.

4. rRNA (ribosomal RNA) associates with a set of proteins to form ribosomes

The function of rRNA in the genetic makeover of the cells cannot be ignored. rRNA is transcribed from ribosomal DNA (rDNA) and then bound to ribosomal proteins to form small and large ribosome subunits.

Together, the small and large ribosome subunits along with various required proteins create the structure of each ribosome. This is how rRNA (ribosomal RNA) associates with a set of proteins to form ribosomes.

Eukaryotic ribosomes are larger and they consist of a 60S large subunit and a 40S small subunit, which come together to form an 80S ribosome particle.

On the other hand, the prokaryotic ribosome is a 70S ribosome that consists of 50S subunit and 30S subunit.

During the translation of the gene, the rRNA which is the part of ribosomes acts as an enzyme connecting tRNA with mRNA. This helps in reading the order of amino acids and linking amino acids together.

You can simply say that mRNA is manual, tRNA carries amino acids, and rRNA is the factory during gene expression.

5. RNAs help in gene regulation

Gene regulation is simply the ability to control the expression of a gene or not. It is a very important aspect of genetic science.

The types of RNA molecules that control gene regulation are messenger RNAs (mRNAs), small RNAs such as microRNAs, and lastly, antisense RNAs.

In a simple molecular biological view, there are two ways of how gene regulation is maintained by RNA to control gene expression.

First, transcription is controlled by limiting the amount of mRNA that is produced from a particular gene. Secondly, RNA regulates and controls the translation of mRNA into proteins.

rRNA as the factory does not bind the mRNA with tRNA until and unless it is required to do so. In such a way, the protein formation is seen only when the need arises.

The small RNAs also help in gene regulation by a variety of mechanisms. They take part in binding to the protein targets, modifying the protein structures, binding to mRNA targets to block it, and in these ways, it regulates the gene expression.

6. RNA viruses have genomes composed of RNA that encodes a number of proteins

We already know that the DNA is an always present genetic molecule in our living cells, and that RNA is transcribed from DNA whenever the need arises during gene expression.

But, do you know that not DNA, but RNA is the always present genetic molecule in some retroviruses like HIV, etc.

In retroviruses, the DNA is produced from RNA via. reverse transcription whenever the need arises during gene expression.

According to the central dogma reverse theory, it is stated that in some viruses (retroviruses) the flow of information is in reverse direction i.e from RNA to DNA.

RNA of these viruses first synthesizes DNA in the presence of Reverse Transcriptase enzyme. DNA then transfers information to RNA and the translation occurs.

So, RNA is very much important for non-living viruses as it is their storehouse of genetic information. So, that’s why it’s said that RNA viruses have genomes composed of RNA that encodes a number of proteins.

Yes, one thing here, RNA viruses are non-living. But when they get into a host cell, they become living and then they create viral proteins in the host cells.

That’s the importance of RNA in viruses, that helps them to transform from non-living to living and develop when inside the host cells.

7. snRNA (small nuclear RNA) helps in the processing of pre-messenger RNA in the nucleus

snRNA helps in RNA splicing of the premature messenger RNA. We’ll know how it is really very important for living eukaryotes.

snRNA is a complex made up of approximately 150 nucleotides along with a set of specific proteins called small nuclear ribonucleoproteins (snRNP). This combination together forms small nuclear ribonucleoproteins (snRNP).

When the non-template (coding) DNA strand acts to facilitate proper transcription to form mRNA then, first the premature messenger RNA is formed.

The premature messenger RNA contains coding RNA sequences (exons) and non-coding sequences (introns). The introns are just useless as they won’t code for amino acids.

So, as a result, the introns need to be removed and the exons need to be joined together from the premature messenger RNA (pre-mRNA). This is known as the splicing of mRNA.

When the introns are removed from the pre-mRNA then, it becomes mature messenger RNA (mRNA). This is a very important step in gene expression.

For many eukaryotes, splicing is carried out in a series of reactions that are catalyzed by a complex of small nuclear ribonucleoproteins (snRNPs).

Thus, it is the reason why and how snRNA (small nuclear RNA) is a very important RNA and helps in the processing of pre-messenger RNA in the nucleus.

8. circRNA (circular RNA) can serve as templates for protein synthesis, similar to mRNA

circRNA isn’t like the normal linear RNA like mRNA, etc. It is a single-stranded RNA that is found in a covalently closed continuous loop joining the 3′ and 5′ ends.

Circular RNAs are more stable than linear RNAs owing to their higher nuclease stability.

This means that they are resistant to exonuclease-mediated degradation and so are presumably more stable.

Earlier it was thought that circRNAs do not code for proteins but more recently, it has been seen that they do code for proteins.

Endogenous circular RNAs were shown to function as post-transcriptional regulators as well along with the formation of proteins.

For example, As competitive inhibitors for microRNAs, circular RNA molecules can be translated into protein even without any IRES sequence, poly-A, or cap structure.

9. RNA helps to provide immunity to the living body

The immune system of our body is very crucial as it protects the body from harmful substances, germs, and destructive cellular changes that could make you ill.

Some RNA molecules are determined to play a vital role in the various mechanisms of the immune system of our body. And, they do these of their own without even creating any proteins.

The RNA molecules that take part in the immunity of our body are mostly non-coding in nature. These RNAs are highly reactive and are strictly involved in the body’s responses to infections.

Just like the RNA molecule called nc886. In humans, this RNA molecule helps to fight against deadly viruses.

When a human cell senses a virus, non-coding RNA (nc886) activates a signaling pathway, and a protein called OAS gets turned on and produces a signaling molecule, which in turn activates another protein.

Then both of the proteins directly defend against the virus as well as activating other parts of the cell’s innate immune system via. various primary and secondary messengers.

This shows how RNA also helps to provide immunity to the living body.