Nucleic acids store and transmit genetic information that we inherit from our ancestors. If you have children, your genetic information in their genome will be recombined and combined with your partner’s genetic information. Your own genome is duplicated whenever each cell divides. In addition, nucleic acids contain certain segments, called genes, that are responsible for the synthesis of all proteins in cells. The properties of genes control the biological characteristics of your body.
General information
Two classes of nucleic acids are distinguished: deoxyribonucleic acid (better known as DNA) and ribonucleic acid (better known as RNA).
DNA is a filamentous chain of genes, which is necessary for the growth, development, life and reproduction of all known living organisms and most viruses.
Changes in the DNA of multicellular organisms will lead to changes in subsequent generations.
DNA is a biogenetic substrate found in all existing living things, from simple living organisms to highly organized mammals.
Many viral particles (virions) contain RNA in the nucleus as genetic material. However, it must be mentioned that viruses lie on the border of animate and inanimate nature, since without a host cell apparatus they remain inactive.
History reference
In 1869, Friedrich Misher isolated nuclei from white blood cells and found that they contain a phosphorus-rich substance, which he called nuclein.
Herman Fischer discovered purine and pyrimidine bases in nucleic acids in the 1880s.
In 1884, R. Gertwig suggested that nucleins are responsible for the transmission of hereditary traits.
In 1899, Richard Altman coined the term "core acid."
And later, in the 40s of the 20th century, scientists Caspersson and Brache discovered a connection between nucleic acids and protein synthesis.
Nucleotides
Polynucleotides are built from many nucleotides - monomers connected together in chains.
In the structure of nucleic acids, nucleotides are isolated, each of which contains:
- Nitrogen base.
- Pentose sugar.
- Phosphate group.
Each nucleotide contains a nitrogen-containing aromatic base attached to a pentose (five-carbon) saccharide, which, in turn, is attached to a phosphoric acid residue. Such monomers, connecting with each other, form polymer chains. They are connected by covalent hydrogen bonds arising between the phosphorus residue of one and the pentose sugar of the other chain. These bonds are called phosphodiester. Phosphodiester bonds form a phosphate-carbohydrate framework (skeleton) of both DNA and RNA.
Deoxyribonucleotide
Consider the properties of nucleic acids in the nucleus. DNA forms the chromosome apparatus of the nucleus of our cells. DNA contains “program instructions” for the normal functioning of the cell. When a cell reproduces its own kind, these instructions are passed on to the new cell during mitosis. DNA has the appearance of a double-stranded macromolecule twisted into a double helical filament.
The nucleic acid contains a phosphate-deoxyribose saccharide skeleton and four nitrogenous bases: adenine (A), guanine (G), cytosine (C) and thymine (T). In a double-stranded helix, adenine paired with thymine (AT), guanine with cytosine (G-C).
In 1953, James D. Watson and Francis H.K. Crick proposed a three-dimensional DNA structure based on low-resolution X-ray crystallographic data. They also referred to the findings of the biologist Erwin Charguff that the amount of thymine in DNA is equivalent to the amount of adenine, and the amount of guanine is equivalent to the amount of cytosine. Watson and Crick, who won the Nobel Prize in 1962 for their contributions to science, put forward the postulate that two strands of polynucleotides form a double helix. The threads, although identical, are twisted in opposite directions. Phosphate-carbon chains are located on the outside of the spiral, and the bases lie inside, where they bind to the bases on another chain through covalent bonds.
Ribonucleotides
The RNA molecule exists as a single-stranded helical filament. The RNA structure contains a phosphate-ribose carbohydrate skeleton and nitrate bases: adenine, guanine, cytosine, and uracil (U). When RNA in the course of transcription is created on a DNA matrix, guanine forms a pair with cytosine (GC) and adenine with uracil (AU).
RNA fragments are used to reproduce proteins inside all living cells, which ensures their continuous growth and division.
There are two main functions of nucleic acids. First, they help DNA by serving as intermediaries that transmit the necessary hereditary information to the myriad of ribosomes in our body. Another major function of RNA is to deliver the correct amino acid needed by each ribosome to create a new protein. Several different classes of RNA are isolated.
Information RNA (mRNA, or mRNA - template) is a copy of the basic sequence of a DNA region obtained by transcription. Informational RNA serves as an intermediary between DNA and ribosomes - the organelles of cells that take amino acids from transport RNA, and use them to build a polypeptide chain.
Transport RNA (tRNA) activates the reading of hereditary data from messenger RNA, as a result of which the process of translation of ribonucleic acid - protein synthesis - starts. It also transfers the necessary amino acids to places where protein is synthesized.
Ribosomal RNA (rRNA) is the main building material of ribosomes. It binds the matrix ribonucleotide in a specific place where it is possible to read its information, thereby starting the translation process.
MicroRNAs are small RNA molecules that act as regulators of many genes.
The functions of nucleic acids are extremely important for life in general and for each cell in particular. Almost all the functions that a cell performs are regulated by proteins synthesized using RNA and DNA. Enzymes, protein products, catalyze all vital processes: respiration, digestion, all types of metabolism.
Differences between the structure of nucleic acids
| Desosciribonucleotide | Ribonucleotide |
| Function | Long-term storage and transmission of hereditary data | Transformation of information stored in DNA into proteins; amino acid transport. A repository of hereditary data for certain viruses. |
| Monosaccharide | Deoxyribose | Ribose |
| Structure | Double stranded spiral shape | Single chain spiral shape |
| Nitrate base | T, C, A, G | U, C, G, A |
Distinctive properties of nucleic acid bases
Adenine and guanine are purines in their properties. This means that their molecular structure includes two condensed benzene rings. Cytosine and thymine, in turn, belong to pyrimidines, and have one benzene ring. RNA monomers build their chains using adenine, guanine and cytosine bases, and instead of thymine they attach uracil (Y). Each of the pyrimidine and purine bases has its own unique structure and properties, its own set of functional groups linked to a benzene ring.
In molecular biology, special one-letter abbreviations are used to indicate nitrogenous bases: A, T, G, C, or U.
Pentose sugar
In addition to a different set of nitrogenous bases, DNA and RNA monomers differ in the pentose sugar included in the composition. The five-atom carbohydrate in DNA is deoxyribose, while in RNA it is ribose. They are almost identical in structure, with only one difference: ribose attaches a hydroxyl group, and in deoxyribose it is replaced by a hydrogen atom.
conclusions
In the evolution of biological species and the continuity of life, the role of nucleic acids cannot be overestimated. As an integral part of all the nuclei of living cells, they are responsible for the activation of all vital processes in the cells.