We explain what nucleic acids DNA and RNA are, their molecular structure, their functions and their importance for living beings.
What are nucleic acids?
Nucleic acids are macromolecules or biological polymers present in the cells of living beings, that is, long molecular chains composed of the repetition of smaller pieces (monomers). In this case, are polymers of nucleotides 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 different shapes.
These macromolecules are contained in all cells (in the cell nucleus in the case of eukaryotes, or in the nucleoid in the case of prokaryotes). Even infectious agents as simple as viruses possess these stable, voluminous 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 acidic substance from the nucleus of different cells that he initially called nucleinbut which turned out to be the first nucleic acid studied.
Thanks to that, later scientists were able to study and understand the form, structure and function of DNA and RNA, forever changing the scientific understanding of the transmission of life.
Types of nucleic acids
Nucleic acids can be of two types: Deoxyribonucleic Acid (DNA) and Ribonucleic Acid (RNA). They differ by:
- Its biochemical functions. While one serves as a “container” for the genetic information, the other serves to transcribe its instructions.
- Its chemical composition. Each comprises a pentose sugar molecule (deoxyribose for DNA and ribose for RNA), and a slightly different set of nitrogenous bases (adenine, guanine, cytosine and thymine in DNA; adenine, guanine, cytosine and uracil in RNA ).
- Its structure. While DNA is a double strand in the shape of a helix (double helix), RNA is single-stranded and linear.
Function of nucleic acids
Nucleic acids, in their respective and specific ways, serve for the storage, reading and transcription of genetic material contained in the cell.
Consequently, intervene in the construction (synthesis) processes of proteins inside the cell. This process occurs whenever the cell produces enzymes, hormones and other peptides essential for the maintenance of the body.
On the other hand, nucleic acids also participate in cell replication that is, the generation of new cells in the body, and in the reproduction of the complete individual, since sexual cells have 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, RNA serves as an operator from said code because it copies it (transcribes it) and takes it to the cellular ribosomes, where the proteins are assembled. It is a complex process that could not occur without these compounds fundamental to life.
Structure of nucleic acids
Each nucleic acid molecule is made up of the repetition of a type of nucleotides, each composed of:
- A pentose (sugar). It is a five-carbon monosaccharide, which can be deoxyribose or ribose.
- a nitrogenous base. It is derived from certain aromatic heterocyclic compounds (purine and pyrimidine). It can be adenine (A), guanine (G), thymine (T), cytosine (C) and uracil (U).
- a phosphate group. Derived from phosphoric acid.
The structural composition of each molecule, in addition, occurs in a double-stranded (DNA) or single-stranded (RNA) helical form, although in the case of prokaryotic organisms, it is common to find circular DNA molecules called plasmids.
Importance of nucleic acids
Nucleic acids are fundamental to 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 an enormous leap forward in the understanding of the chemical foundations of life.
That's why, DNA protection is essential for life of the individual and the species. Toxic chemical agents (such as ionizing radiation, heavy metals or carcinogenic substances) can cause alterations in nucleic acids, and cause diseases that, in certain cases, can be transmissible to future generations.
Continue with: Biomolecules
References
- “Nucleic acids” on Wikipedia.
- “Nucleic acids” at KhanAcademy.
- “Nucleic acid” at National Human GenomeResearch Institute.
- “Nucleicacids” in ScienceDirect.
- “Nucleic acid” in The Encyclopaedia Britannica.
- Biology: Solomon E., Berg L., Martin D. (2013) 9th Edition. Cengage Learning Publishing.
- Cellular and Molecular Biology. From Robertis Edward, Hib José. (2012) 16th ed. Promed Editorial.
