RNA

By Mihir Kapse | 1 October 2024

In any living cell, there are mainly two types of nucleic acids – DNA and RNA. RNA (ribonucleic acid) is a polymeric biomolecule which is essential for most biological functions, either by performing the function itself or by acting as a template to produce proteins. It is a biopolymer of nucleotides. These nucleotides may be made up of four different types of nitrogenous bases - adenine, guanine, cytosine and uracil (in DNA, thymine is present instead of uracil), that is, A G C and U.

In 1910, Phoebus Levene distinguished between DNA and RNA. He identified that RNA contains ribose sugar, while DNA contains deoxyribose. He also discovered the aforementioned difference in nitrogenous bases present in the nucleotides.

Thereafter, it was discovered that there are actually three different types of RNA – namely messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA). They are distinguished based on the functions they perform. All RNA molecules are synthesized from a DNA template through a process called transcription.

  1. mRNA (messenger RNA): As the name suggests, it is messenger molecule. It acts as a carrier of genetic information for a protein sequence from DNA to ribosomes, the protein factory of cell. Each sequence of three nucleotides in mRNA is called a codon. A specific type of amino acid corresponds to particular codon. This is known as the genetic code.

  2. tRNA (transfer RNA): tRNA is a small biopolymer with about 70-80 nucleotides. Each tRNA has an anticodon region that is complementary to the mRNA’s codon. The anticodon part pairs up with the codon part of mDNA during the process of translation, and also binds to the amino acid corresponding to the codon. The main function of tRNA is to act as an adapter molecule and help translate the genetic code of mRNA into the sequence of amino acids that make up the protein.

  3. rRNA: (ribosomal RNA): It is a catalytic RNA, and constitutes a large portion of a ribosome. It hosts the translation process between tRNA and mRNA, within the ribosome.

Initially, it was thought that RNA could not be used for any therapeutic purposes due to its short half-life. However, with advances in technology, we are now able to stabilize RNA molecules, opening doors to its various applications in therapeutics. RNA-based vaccines are on the rise today, which are easier to produce than traditional vaccines.

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