Definition, Examples & Functions of DNA and RNA Nucleic Acids

We explain what DNA and RNA nucleic acids are, their molecular structure, their functions, and their importance for living things.

1. What are nucleic acids?

Nucleic acids are macromolecules or biological polymers present in the cells of living things , that is, long molecular chains composed from the repetition of smaller pieces known as monomers. In this case, they are nucleotide polymers linked by phosphodiester bonds .

There are two known types of nucleic acid: DNA and RNA . Depending on their type, they can be more or less vast, more or less complex, and can have various forms.

These macromolecules are contained in all s cells (in the cell nucleus in the case of eukaryotes , or in the nucleoid in the case of prokaryotes ). Even beings as simple and unknown as viruses possess these stable, bulky and primordial macromolecules.

Nucleic acids were discovered at the end of the 19th century, by Johan Friedrich Miescher (1844-1895). This Swiss doctor isolated an acid substance from the nucleus of different cells that he initially called nuclein , but which turned out to be the first nucleic acid studied.

Thanks to this, later scientists were able to study and understand the shape, structure and functioning of DNA and RNA, forever changing the scientific understanding of the transmission of life.

2. Types of nucleic acids

Nucleic acids can be of two types: Deoxyribonucleic Acid (DNA) and Ribonucleic Acid (RNA).

Both are distinguished by :

• Its biochemical functions : while one serves as a “container” for genetic information, the other serves to materialize its instructions.
• Its chemical composition : each one comprises a different molecule of pentose sugar (deoxyribose for DNA and pentose for RNA), and a set of slightly different nitrogen bases (adenine, guanine, cytosine and thymine in DNA; adenine, guanine, cytosine and uracil in the RNA).
• Its structure : while the DNA is a double chain in the form of a helix (double helix), the RNA is single stranded and linear.

3. Function of nucleic acids

Nucleic acids, in their respective and specific way, serve for the storage, reading and transcription of the genetic material contained in the cell .

Consequently, they are involved in the processes of construction (synthesis) of proteins inside the cell. It occurs whenever it makes enzymes, hormones and other substances essential for the maintenance of the body.

On the other hand, nucleic acids also participate in cellular replication , that is, in the generation of new cells in the body, and in the reproduction of the entire individual, since sex cells possess half of the complete genome (DNA) of Each parent

DNA encodes all of the organism’s genetic information through its nucleotide sequence. In that sense, we can say that DNA operates as a nucleotide template

Instead, the RNA serves as an operator from that code , copying it and taking it to the cellular ribosomes, where the proteins will be assembled . As will be seen, it is a complex process that could not occur without these fundamental compounds for life.

4. Structure of nucleic acids

Each nucleic acid molecule is made up of the repetition of one type of nucleotide, each composed of the following:

• A pentose (sugar) , that is, a five-carbon monosaccharide, which can be deoxyribose or ribose.
• A nitrogen base , derived from certain aromatic heterocyclic compounds (purine and pyrimidine), and which may be adenine (A), guanine (G), thymine (T), cytosine (C) and uracil (U).
• A phosphate group , derived from phosphoric acid.

In addition, the structural composition of each molecule is given in a three-dimensional double helix (DNA) or single strand (RNA) form, although in the case of prokaryotic organisms it is common to find a single stranded circular DNA.

5. Importance of nucleic acids

Nucleic acids are essential for life as we know it, since they are essential for protein synthesis and for the transmission of genetic information from one generation to another (inheritance). The understanding of these compounds represented at the time a huge leap forward in the understanding of the chemical foundations of life .

Therefore,  the protection of DNA is fundamental for the life of the individual and the species. Toxic chemical agents (such as ionizing radiation, heavy metals or carcinogenic substances) can cause alterations in the nucleic acid molecule, causing diseases that, in certain cases, can become transmissible to future generations.