Structure and Functions of RNA

Functions of RNA

RNA, an abbreviation of ribonucleic acid, a complex high molecular weight compound that functions in the synthesis of cellular proteins and replaces DNA ( deoxyribonucleic acid) as a carrier of genetic codes in some viruses. RNA consists of ribose nucleotides (nitrogenous bases bound to a ribose sugar) connected by phosphodiester bonds, forming variable length chains. Adenine, guanine, cytosine, and uracil are the nitrogen bases in RNA, which replace thymine in DNA. RNA, ribonucleic acid is a type of nucleic acid that contributes to protein synthesis.

RNA is a ribonucleic acid that helps with protein synthesis in our bodies. The production of new cells in the human body is responsible for this nucleic acid. Usually, it is obtained from the molecule of DNA. RNA is similar to DNA, the only difference being that it has a single strand, unlike the DNA that has two strands and consists of a single ribose sugar molecule within it. Thus the name is Ribonucleic acid. RNA is also called an enzyme, as it helps with chemical reactions in the body.

Basic Structure of RNA

The basic RNA structure is shown in the following figure-

The ribonucleic acid has all the components the same as that of the DNA with only 2 main differences within it. RNA has the same bases of nitrogen called adenine, guanine, cytosine as the DNA, except for the thymine that is replaced by uracil. Adenine and uracil are regarded as the major RNA building blocks and both form base pairs with the help of 2 hydrogen bonds.RNA resembles a hairpin structure and like the nucleotides in DNA, nucleotides are formed in this ribonucleic material(RNA). Nucleosides are nothing but the groups of phosphates which also sometimes help in the production of nucleotides in DNA.

Functions of RNA

Ribonucleic acid – RNA, which consists mainly of nucleic acids, is involved in a variety of cell functions and is found in all living organisms including bacteria, viruses, plants, and animals. These nucleic acid functions in cell organelles as a structural molecule, and are also involved in biochemical reaction catalysis. The various types of RNA participate in a separate cellular cycle. The primary functions of RNA:

  • Facilitate the translation of DNA into proteins

  • Functions as an adapter molecule in  protein synthesis

  • Serves as a messenger between the DNA and the ribosomes.

  • They are the carrier of genetic information in all living cells

  • Promotes the ribosomes to choose the right amino acid which is required in building up of new proteins in the body. 

History of RNA

Nucleic acids were first discovered in 1868 by Friedrich Miescher who named the substance 'nuclein' because it was located in the nucleus and this led to RNA being discovered. The key milestone in RNA history is outlined below;

Some of the highlights of RNA molecules are given below,

  • Due to its sensitivity to alkaline – OH group on the ribose, RNA was distinctly different from DNA

  • The key energy source and building blocks for RNA were to be ATP and GTP.

  • The three bases common to RNA and DNA were adenine, cytosine, and guanine while Uracil is present in the RNA instead of thymine.

RNA Types

There are different types of RNA out of which the human body is most well-known and most commonly studied:

  • TRNA-RNA transfer

  • The transfer RNA is responsible for selecting the correct protein or the amino acids that the body requires to help the ribosomes in-turn. It is at the endpoints of any amino acid. This is also called soluble RNA and constitutes a connection between messenger RNA and amino acid

  • rRNA-Ribosomal RNA

  • The rRNA is the ribosome portion and is located within a cell's cytoplasm, where ribosomes are found. In all living organisms, the Ribosomal RNA is mainly involved in the synthesis and translation of mRNA into proteins. The rRNA is composed primarily of cellular RNA and is the most prevalent RNA in the cells of all living organisms

  • mRNA – Messenger RNA.

As the name itself says, this RNA is responsible for bringing the genetic material to the ribosomes and insists on what kind of protein the body needs. It is therefore called messenger RNA. This m-RNA is usually involved in the transcription process, or during the process of protein synthesis.

Fun Facts -

RNA is an acronym for ribonucleic acid, which is a nucleic acid. There are many different kinds now known. 

RNA is physically distinct from DNA: DNA contains two intercoiled strands, while RNA contains just one strand. RNA also contains different DNA bases. These are the following bases -

  1. Adenine

  2. Guanine 

  3. Cytosin 

  4. Uracil

Adenine also binds to uracil, and guanine also binds to cytosine. Therefore, we state that adenine is complementary to uracil and that guanine is complementary to cytosine. The first three bases are also found in DNA, but uracil replaces thymine as a supplement to adenine.

RNA also contains ribose rather than deoxyribose present in DNA. These differences mean that RNA is chemically more reactive than DNA. This makes it the most suitable molecule to take part in cell reactions. 

RNA is the carrier of genetic information for certain viruses, particularly retroviruses such as the HIV virus. That is the only exception to the general rule that DNA is a hereditary substance.

FAQ (Frequently Asked Questions)

1. What are the different types of RNA?

For the translation of genetic information (DNA) into proteins, three different types of RNA are identified, present in prokaryotic and eukaryotic organisms.

• The genetic information is carried by messenger RNA ( mRNA)

• RNA transfer (tRNA) acts as the physical connection between mRNA and proteins

• Ribosomal RNA ( rRNA) occurs on protein-synthesizing ribosomes


2. Explain the functions of RNA?

Analogous rRNAs from different species fold into a similar three-dimensional structure that contains numerous stem-loops and protein, mRNA, and tRNA binding sites. As a ribosome travels along an mRNA a region of the rRNA molecule in each ribosome sequentially binds the amino-activated ends of incoming tRNAs and is likely to catalyze the formation of peptide bonds. Thus it synthesizes a protein.