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 every time 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
There are two classes of nucleic acids: deoxyribonucleic acid (better known as DNA) and ribonucleic acid (better known as RNA).
DNA is a threadlike chain of genes that 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 the simplest living organisms to highly organized mammals.
Many viral particles (virions) contain RNA in the nucleus as genetic material. However, it should be mentioned that viruses lie on the border of animate and inanimate nature, since without the cellular apparatus of the host they remain inactive.
Historical background
In 1869, Friedrich Miescher isolated nuclei from white blood cells and found that they contained a phosphorus-rich substance he called nuclein.
Hermann Fischer discovered purine and pyrimidine bases in nucleic acids in the 1880s.
In 1884, R. Hertwig suggested that nucleins are responsible for the transmission of hereditary traits.
In 1899, Richard Altmann coined the term "core acid".
And later, in the 40s of the 20th century, scientists Kaspersson and Brachet discovered a link between nucleic acids with 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, when combined with each other, form polymericchains. They are connected by covalent hydrogen bonds that occur between the phosphorus residue of one and the pentose sugar of the other chain. These bonds are called phosphodiester bonds. Phosphodiester bonds form the phosphate-carbohydrate backbone (skeleton) of both DNA and RNA.
Deoxyribonucleotide
Let's consider the properties of nucleic acids located in the nucleus. DNA forms the chromosome apparatus of the nucleus of our cells. DNA contains the "software 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 thread.
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 pairs with thymine (A-T), guanine pairs with cytosine (G-C).
In 1953, James D. Watson and Francis H. K. Crick proposed a three-dimensional structure of DNA based on low-resolution X-ray crystallographic data. They also referred to biologist Erwin Chargaff's findings that in DNA, the amount of thymine 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, postulated that two strands of polynucleotides form a double helix. The threads, although they are identical, twist in opposite directions.directions. The phosphate-carbon chains are located on the outside of the helix, while the bases lie on the inside, where they bond to bases on the other chain via covalent bonds.
Ribonucleotides
The RNA molecule exists as a single-stranded spiral thread. The structure of RNA contains a phosphate-ribose carbohydrate skeleton and nitrate bases: adenine, guanine, cytosine and uracil (U). When RNA is created on the DNA template during transcription, guanine pairs with cytosine (G-C) and adenine with uracil (A-U).
RNA fragments are used to reproduce proteins within all living cells, which ensures their continuous growth and division.
There are two main functions of nucleic acids. Firstly, they help DNA by serving as intermediaries that transmit the necessary hereditary information to the countless ribosomes in our body. The other main function of RNA is to deliver the correct amino acid that each ribosome needs to make a new protein. There are several different classes of RNA.
Messenger RNA (mRNA, or mRNA - template) is a copy of the basic sequence of a DNA segment obtained as a result of transcription. Messenger RNA serves as an intermediary between DNA and ribosomes - cell organelles that accept amino acids from transfer RNA and use them to build a polypeptide chain.
Transfer RNA (tRNA) activates the reading of hereditary data from messenger RNA, resulting in the translation processribonucleic acid - protein synthesis. It also transports the right amino acids to where protein is synthesized.
Ribosomal RNA (rRNA) is the main building block of ribosomes. It binds the template ribonucleotide in a certain place where it is possible to read its information, thereby starting the translation process.
MiRNAs 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
| Dezoskiribonucleotide | Ribonucleotide | |
| Function | Long-term storage and transmission of hereditary data | Transformation of information stored in DNA into proteins; transport of amino acids. Storage of hereditary data of some viruses. |
| Monosaccharide | Deoxyribose | Ribose |
| Structure | Double-stranded spiral shape | Single strand helical shape |
| Nitrate bases | T, C, A, G | U, C, G, A |
Distinctive properties of nucleic acid bases
Adenine and guanine bytheir properties are purines. This means that their molecular structure includes two fused 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 add uracil (U). Each of the pyrimidine and purine bases has its own unique structure and properties, its own set of functional groups linked to the benzene ring.
In molecular biology, special one-letter abbreviations are used to denote 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 their pentose sugar. 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 adds a hydroxyl group, while 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 nuclei of living cells, they are responsible for the activation of all vital processes occurring in cells.
