What is RNA? 3 Types, Function, and Structure, RNA and DNA

What is RNA?

RNA (Ribonucleic Acid) is one of the elemental nucleic acids for life, responsible together with DNA (deoxyribonucleic acid) for the work of protein synthesis and genetic inheritance.

This acid is present inside both prokaryotic and eukaryotic cells, and even as the only genetic material of certain types of viruses (RNA viruses), and consists of a molecule in the form of a single chain of nucleotides (ribonucleotides) formed in turn by a sugar (ribose), a phosphate and one of the four nitrogenous bases that make up the genetic code: adenine, guanine, cytosine or uracil.

It is generally a linear and single-stranded (single-stranded) molecule and fulfills a variety of functions within the complex of the cell, which makes it a versatile executor of the information contained in DNA.

The understanding of how RNA operates and its importance for life and evolution, made possible the emergence of theses on the origin of life, such as the one that intuits in 2016 that the molecules of this nucleic acid were the first forms of life in existing (in the RNA world Hypothesis ).

What is RNA? 3 Types, Function, and Structure, RNA and DNA

See also: Bacteria

Definition of RNA 

Ribonucleic acid (RNA) is a polymeric molecule required in genes of coding, decoding, regulation, and expression in various biological roles. It is actually a complex compound of high molecular weight that functions in cellular protein synthesis and replaces DNA as a carrier of genetic codes in some viruses. RNA and DNA are nucleic acids, and together with lipids, proteins and carbohydrates, constitute the four major macromolecules necessary for all known forms of life. RNA is a single multi-nucleotide chain fibrous molecule in which units of phosphate and ribose sugars are established in alternating order. RNA is widely used to mimic DNA genes in the body. At the same time, RNA functions in transporting other genetic material into cells.

What is RNA full form?

The full form of RNA is ribose nucleic acid. 

Who discovered RNA?

The RNA was discovered by Frederick Meicher.

RNA  was discovered along with DNA in 1867, by Friedrich Meischer, who called them nuclein and isolated them from the cell nucleus, although their existence was later proven in prokaryotic cells, without a nucleus. The RNA synthesis mode in the cell was later discovered by the Spanish Severo Ochoa Albornoz, winner of the Nobel Prize in Medicine in 1959

What is RNA in simple terms?

The full name of RNA is Ribose Nucleic Acid. It is made up of a single polyribonucleotide chain. It contains Ribonucleoside and Ribonucleotide. There are four types of ribonucleotides –

  • Adenylic acid
  • Guanylic acid
  • Cytidylic Acid
  • Uridylic acid

The structure of RNA

Nucleotides are made up of a monosaccharide sugar molecule called ribose.

Both DNA and RNA are made up of a chain of units known as monomers, which are repeated and are called nucleotides; These are linked together by negatively charged phosphodiester bonds. Each of these nucleotides is made up of:

  • A monosaccharide sugar molecule is called ribose (other than deoxyribose in DNA).
  • A phosphate group (salts or esters of phosphoric acid).
  • A nitrogenous base: Adenine, Guanine, Cytosine, or Uracil (in the latter it differs from DNA, which has Thymine instead of Uracil).

These components are organized based on three structural levels, which are:

  • Primary. The linear sequence of nucleotides defines the following structures.
  • Secondary. Since RNA folds on itself due to intramolecular base pairing, its secondary structure refers to the shape it takes during folding: helix, loop, hairpin loop, bulge, pseudo-knot, etc.
  • Tertiary. Although RNA does not form a double helix like DNA in its structure, it does tend to form a single helix as a tertiary structure, as its atoms interact with the surrounding space.

 Function of RNA

RNA fulfills numerous functions, the most important being protein synthesis, in which it copies the genetic order contained in DNA to use it as a standard in the manufacture of proteins and enzymes and various substances necessary for the cell and the organism. To do this, it goes to the ribosomes, which operate as a kind of molecular protein factory, and it does so by following the pattern printed by DNA.

3 Types of RNA

Types of RNA-There are several types of RNA, depending on their primary function:

  • Messenger or coding RNA (mRNA).  It is responsible for copying and carrying the exact sequence of amino acids from DNA to the ribosomes, where instructions are followed and proteins are synthesized. In prokaryotic cells, more than one polypeptide chain is formed from the same mRNA. Therefore, these mRNAs are called polycistronic RNA. Whereas eukaryotic cells contain information for the synthesis of only one polypeptide chain from one mRNA. Which is called monocistronic RNA.
  • Transfer RNA (tRNA).  These are short polymers of 80 nucleotides that have the mission of transferring the pattern copied by the mRNA to the ribosomal RNA, serving as an assembly machine, choosing the correct amino acids based on the genetic code. It is the shortest RNA. In which 75–95 ribonucleotides are found. It transfers amino acids to the A-site of the ribosome at the time of protein synthesis. There are specific tRNAs for each 20 amino acid. Each tRNA is specific to the same amino acid. And carries amino acids from the cytoplasm to the ribosome for protein synthesis. Therefore, tRNA or transfer RNA in a cell is also called soluble RNA or Adaptor RNA. T-RNA comprises 16–18% of the total RNA in a cell.
  • Robert Hawley presented the cover Clover Leaf structure according to which tRNA has four arms –

Acceptor Arm –

This arm has 5 ‘and 3’ ends. CCA (cytosine-cytosine adenine) are alkali at the 3 ‘end and G (guanine) at the 5’ end. The amino acid has a carboxyl group (-COOH). Connects via CCA’s adenosine at the 3 ‘end.

Anticodon Arm –

This arm is the opposite arm of the receptive arm. It has a special sequence of three bases. Which is called Pratikodon. These replicons are the prototypes of the codons located on the mRNA. For example, if mRNA contains AUG codons, then tRNA will be UAG codon.

TψC arm

This arm helps to link tRNA to the ribosome.

DHU arm

This arm helps to attach to the enzyme. This DHU’s full name is dihydrouridine, which is an uncommon alkali.

  • tRNA contains some unusual bases such as Inosine and Dihydrouridine etc.
  • Ribosomal RNA (rRNA). Its name comes from the fact that it is found in the ribosomes of the cell, where they are combined with other proteins. They operate as catalytic components to “weld” the newly assembled proteins onto the mRNA template. They act, thus, as ribozymes. rRNA is a component of ribosomes. It forms 80% of the Ribosome. Ribosomes consist of ribonucleoproteins and rRNA. Synthesis of rRNA results from information contained in ribosomal genes found in the nucleolar organizer region of the chromosome. 

80% of the total RNA found in a cell is rRNA.The 70s type of ribosome is found in prokaryotic cells, mitochondria, and lobes. Which consists of two sub-units 50s and 30s.The 50s ribosome contains 23s rRNA, 5s rRNA. Whereas the 30s ribosome contains 16s rRNA.About 3000 ribonucleotides in 23s rRNA, about 120 ribonucleotides in 5s rRNA, 16s rRNA 1500 ribonucleotides are found.

The 80s type of ribosome is found in the eukaryotic cell. Which consists of two sub-units 60s and 40s.

The 60s ribosome contains 28s, 5.8s, and 5s rRNA. Whereas the 40s ribosome is 18s rRNA. There are 5000 ribonucleotides in 28s rRNA, 160 ribonucleotides in 5.8s rRNA, 120 ribonucleotides in 5s rRNA. Whereas 18s rRNA contains 1800 ribonucleotides.

rRNA is a structural molecule. Whereas tRNA and rRNA are functional molecules.

  • The units of the ribosome and the rRNA found in them are represented by the Swedberg Unit (S). It exhibits the sedimentation rate of these molecules.
  • Regulatory RNAs. They are complementary pieces of RNA, in specific regions of mRNA or DNA, that can perform various tasks: interference in replication to suppress specific genes (RNAi), activators of transcription (antisense RNA), or regulate expression gene (long cRNA).
  • Catalyst RNA.  Pieces of RNA that operate as biocatalysts, operating on the synthesis processes themselves to make them more efficient or ensure their correct development, or even put them fully into operation.
  • Mitochondrial RNA. Since the cell’s mitochondria have their protein synthesis system, they also have their forms of DNA and RNA.


RNA is a smaller and more complex molecule than DNA.

The difference between RNA and DNA is based, first of all, on their constitution: as has been said, RNA has a different nitrogen base (uracil) than thymine and is composed of a different sugar than deoxyribose (ribose).

Apart from this, DNA has a double helix in its structure, that is, RNA is a smaller and more complex molecule, which has a much shorter life span in our cells.

However, their differences are more profound, since DNA serves as an information bank, an ordered pattern of the elemental sequence that allows us to build the proteins in our body; while the RNA is its reader, transcriber, and executor: the one in charge of reading the code, interpreting it and materializing it.

DNA means Deoxyribo Nucleic Acid, RNA means Ribo Nucleic Acid, both of which are used to give genetic information, but there are some differences between them: –

  • DNA contains deoxyribose sugars, RNA contains sugars ribose.
  • DNA is mainly found in the nucleus, RNA is found in both the nucleus and cytoplasm.
  • DNA contains bases – adenine, guanine, thymine, cytosine, uracil replaces base thymine in RNA.
  • The main difference between Ribose and Deoxyribose is that in Ribose, a group of -OH is more than deoxyribose.
  • DNA is a double-stranded molecule, RNA is a single-stranded molecule.
  • DNA is self-generated while RNA can be extracted from DNA if needed.
  • DNA can be damaged by ultraviolet rays whereas it does not affect RNA.
  • The base pairing of DNA is AT and GC but the base pairing of RNA is AU and GC.
  • Most of the amount of DNA is in the nucleus, RNAs are engaged in ribosomes. DNA conducts genetic functions, helps select amino acids by taking various orders outside the RNA nucleus, and assists in protein modification.

The function of DNA is to transfer the genes of parents to their children while rRNA protein synthesis carries the tRNA mRNA from the nucleus to the endoplasmic reticulum and carries the code of the type of mRNA protein.

What is RNA? 3 Types, Function, and Structure, RNA and DNA
What is RNA? 3 Types, Function, and Structure, RNA and DNA

What is RNA? 3 Types, Function, and Structure, RNA and DNA


Categories: Genetics