Nucleic acids are the custodians of genetic information

Nucleic acids (nucleus - nucleus) -organic compounds with which all the basic processes of existence of living matter are connected. These biopolymers were first isolated by F. Misher (1968) from the nuclei of leukocytes. A little later, nucleic acids were identified in all human cells, animals and plants, in microbes and viruses. Thus, it was proved that these biological compounds are contained in all cells of organisms, are the main carriers of hereditary information, take part in the biosynthesis of body proteins.

Nucleic Acid Presentation

Nucleic acids are prostheticgroups of nucleoproteins. The final products of their hydrolysis are purine and pyrimidine bases, pentoses and phosphoric acid. The chemical composition distinguishes deoxyribonucleic (DNA) and ribonucleic (RNA) acids. The DNA composition includes monosaccharide - deoxyribose, RNA - ribose. These compounds differ among themselves by nitrogenous bases, molecular structure, cellular localization, and also functions.

Compounds, the molecule of which consists of purineor pyrimidine bases and pentoses (ribose, deoxyribose), are called nucleosides. The name of the nucleoside is determined by the nitrogen compound, which is included in its structure. For example, a nucleoside, which includes adenine is called adenosine, guanine - guanosine, cytosine - cytidine, uracil - uridine, thymine - thymidine. Depending on the carbohydrates that make up the molecules, they distinguish between rubonucleosides and deoxyribonucleosides.

In addition to the basic nitrogenous bases, nucleic acids The and the so-called minor bases of the purine and pyrimidine series (1-methyladenine, dihydrouracil, 1-methylguanine, 3 methyluracil, pseudouridine, etc.).

Nucleotides are phosphoric estersnucleosides. The nucleotide molecule includes purine or pyrimidine bases, pentose (ribose or deoxyribose), and a phosphoric acid residue that binds to the fifth or third carbon atom of pentose.

Nucleic acids structure and function.

Individual nucleotides are joined together atThis is formed by di-, tri-, tetra-, penta-, hexa-, hepta- and polynucleotides, that is, nucleic acids. Nucleic acids consist of hundreds and thousands of individual nucleotides that are joined together by a hydroxyl group located near the 3'th atom of the carbon atom of the pentose of one nucleotide with a phosphoric acid residue that is located near the 5 'th carbon atom of the pentose of the next nucleotide.

DNA is the main genetic materialall living biosystems. In organisms, with the exception of bacteria and viruses, it is localized in the cell nuclei. An insignificant amount of this acid is concentrated in the mitochondria and chloroplasts.

Ribonucleic acids have been identifiedpractically in every cell fraction. The greatest amount of RNA is concentrated in ribonucleoprotein components - ribosomes. It should be said that the bulk of RNA is contained in the cytoplasm, and only 10-15% is part of the nucleus.

RNA, taking into account cellular localization, biological function, molecular weight, is divided into three types: ribosomal, transport and matrix.

Ribosomal RNAs are localized incytoplasmic granules of the ribosome, where they are firmly bound to the protein. They are characterized by high molecular weight. Transport RNAs are mainly in the cell's hyaloplasm, nuclear fluid in mitochondria and chloroplasts. They have a small molecular weight (up to 40 thousand daltons). Their main function is the transportation of activated amino acids from the amino acid complex - AMP-enzyme to the site of protein biosynthesis, that is, to the ribosomes. Scientific studies have shown that each amino acid has its own individual tRNA. Today, more than 60 types of transport RNA are known.

Matrix RNA (informational RNA). Each molecule of mRNA in the process of synthesis in the nucleus receives information from DNA and transfers it to the ribosomes, where it is realized during protein biosynthesis.