Characteristics of RNA (Ribonucleic acid)

Thanks to various molecular methodologies that include in vitro transcription, sequencing and in vivo and in vitro expression, among other analyses, it has been possible to define what RNA is.

Some authors refer to RNA as RNA, which stands for Ribonucleic acid . Discover more about what RNA is and its functions in this article, where we also talk about its characteristics.

What is RNA

Ribonucleic acid, acronym RNA, or RNA in English, is a type of nucleic acid formed by a chain of ribonucleotides , organic molecules formed by a phosphate molecule, a sugar (ribose) and a nitrogenous base that can be adenine (A ), guanine (G), cytosine (C) or uracil (U). This uracil replaces thymine, which is one of the four nitrogenous bases that make up DNA.

The first studies on ribonucleic acid date back to the 1940s. It is said to be a prebiotic molecule that has existed for approximately 3.8 million years.

Ribonucleic acid is present in prokaryotic and eukaryotic cells , as well as in some types of viruses. It is almost always represented by a single chain of ribonucleotides, unlike DNA, which is displayed in the form of a helix or two chains most of the time, although this is not always the case.

RNA is almost always represented in single-stranded form, but it is also possible to find double-stranded RNA, the latter being the least likely.

Characteristics of RNA

RNA is responsible for directing the intermediate stages of amino acid synthesis . It does not directly store information like DNA, but rather transfers it. By passing information, it can be transformed from a string of nucleic acids to a string of amino acids. Therefore, DNA cannot act alone, and uses RNA to transfer information during protein synthesis.

RNA actually fulfills more functions than DNA , therefore, it is much more versatile. When the DNA strand is copied to RNA, every three DNA nucleic acids make three RNA nucleic acids. These three RNA nucleic acids are transformed into an amino acid.

There are different types of RNA according to their functions . Synthesizing amino acids is quite complex, so several stages in the process are required to carry it out. These different types are:

  • rRNA, whose abbreviation means ribosomal RNA .
  • nRNA meaning nucleolar RNA .
  • mRNA, which means messenger RNA .
  • tRNA, which means transfer RNA .

Functions of RNA

As we have mentioned, depending on the function of the RNA, we talk about one type or another. Therefore, below we are going to see what the characteristics and functions of RNA in particular are.

ribosomal RNA – rRNA

It is identified by being found only in ribosomes, found in eukaryotic and prokaryotic cells. However, these ribosomes have something special: they are made up of two substructures of different sizes; one bigger than the other. These substructures are made up of long chains of RNA.

Ribosomes are structures formed by a combination of proteins and ribonucleic acids, which in turn are formed by two subunits that can join or separate, according to their activity. Ribosomes intervene in protein synthesis by assembling amino acids according to the order predetermined by the base sequence of the messenger RNA.

Ribosomal rRNA comes from nucleolar RNA.

Nucleolar RNA – snRNA

It is a long molecule of ribonucleic acid that, once synthesized, is located in the nucleolus of eukaryotic cells. Ribosomal RNA is obtained from nucleolar RNA.

Messenger RNA – mRNA

We see it in the transcription process. That is, when a strand of DNA is read and transcribed , a strand or chain of messenger RNA is obtained. What it does is remove the message from the nucleus of the cell and then pass it to the cytoplasm.

Right there, in the cytoplasm, the ribosomes are located, which will receive the messenger RNA to translate it into amino acids that will finally form proteins. The mRNA represents 3 to 5% of the total cellular RNA and its size will depend on the transcribed gene. Simply put, mRNA is the template for protein synthesis .

mRNA can bind to rRNA thanks to tRNA.

Transfer RNA – tRNA

This type of RNA has the function of recognizing each group of three nucleotides (triplet) of the messenger RNA in a complementary manner. In this way, thanks to complementary recognition, for each triplet of messenger RNA that the transfer RNA reads, it binds an amino acid.

This is how the messenger RNA, through the action of the transfer RNA within the ribosome, can form a chain of nucleotides into a chain of amino acids. The specific part of tRNA AND mRNA that join is called anticodon in the case of tRNA and codon in the case of mRNA.

In short, tRNA is the carrier of amino acids for protein synthesis.

Steps in the transcription process

Transcription is the process where a segment of DNA is transcribed into RNA . Complete the following steps that we are going to number.

  • First step : the polymerized RNA (set of proteins) is located in the promoter region of the gene.
  • Second step : the DNA double helix opens.
  • Third step : the polymerized RNA advances on the DNA, generating a chain of RNA.
  • Fourth step : the polymerized RNA finishes transcription.
  • Fifth step : the RNA is processed to acquire its biological function (RNA or protein).

Steps in the translation process

Translation is the process where a protein is synthesized by a ribosome , from an RNA molecule.

  • First step : RNA binds to the ribosome.
  • Second step : the ribosome is responsible for reading the RNA molecule.
  • Third step : the essential amino acid is added every time 3 nucleotides of RNA are read. The first is called Methionine.
  • Fourth step : The ribosome separates once translation is completed.
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