What is the composition of DNA is sugar? Chemical basis of DNA structure

It's amazing to see how similar parents and children are to each other. Or, on the contrary, are completely different from brothers and sisters, and from father and mother. Why is it so and what does it depend on? What structures are responsible for the preservation, consolidation, transfer and manifestation of traits from descendants from parents?

This role belongs to the nucleic acids that form the chromosomes. They are the molecules that perform the functions of all processes associated with heredity and variability. A special prerogative in this belongs to DNA molecules.

The history of the discovery of nucleic acids

For a long time, such molecules were not known. However, in 1869, scientist Mischer discovered a mixture of DNA and RNA as a result of research, and then managed to establish their belonging to acids. He did this on the basis of studying leukocytes in pus.

Since then, the active study of these compounds began. Many scientists have tried to establish the chemical composition of DNA and RNA. Understand their nature, the essence of the structure and biological role. A great contribution to this business was made by such people as:

• A. N. Belozersky.
• Thomas Morgan.
• C. Bridges.
• A. Meller.
• G. de Vries.
• A. Sturtevant.
• GA Nadson.
• A. S. Serebrovsky.
• NP Dubinin.
• TS Filippov and others.

In the period from 1900 to the present time, the nature of nucleic acids, the chemical basis of the structure of DNA, its features and biological significance was elucidated. Discoveries have been made that allow this molecule to be considered the universal basis of all living things.

Research in the field of genetics has made it possible to establish the relationship between DNA, genome and chromosomes, to decipher the genetic code of many living things. This was important for understanding the structure of wildlife, the mechanisms of its operation.

The chemical composition of the chromosomes was also determined. It was found out that their basis is a nucleic acid molecule having a specific structure.

DNA: a general characteristic

Full decoding of the abbreviation of the name - deoxyribonucleic acid. Along with RNA, this acid belongs to a number of nucleic acids. Its name was given for the fact that the composition of DNA includes sugar. Its name is deoxyribose.

The chemical composition of DNA and RNA is very similar, the difference is just the same in the carbohydrate forming the molecule. RNA is a ribose.

In general, the molecule of deoxyribonucleic acid is a complex double-stranded macromolecule, which has a huge molecular weight and a diverse composition. Therefore, most often the graphic representation of this connection has the form of two strands, united by transverse steps - links.

In 1953, Chargaff and his collaborators were able to uncover the completely internal structure and composition of the molecule, which was of great importance for all molecular biology and science as a whole. It became evident that the DNA composition includes the sugar of the five-carbon base (pentose), purine and pyrimidine bases and orthophosphoric acid residues.

This allowed not only to further decipher the very structure of the compound, but also to study the properties, physical and chemical. The biological role and significance for the organism was defined as fundamental, universal and specific for each being.

Chemical composition

If we characterize the internal atomic and molecular composition of the nucleic acid molecule, we can distinguish several basic types of compounds:

• Pentose - deoxyribose (carbohydrate monosaccharide);
• Organic bases - purine (adenine and guanine), pyrimidine (cytosine and thymine);
• Residues of phosphoric acid with free bonds.

This, in general, all the chemical bases of the structure of DNA. Another thing is that the connection of all these components is not simple, but is a complex and unique process. Thus, the deoxyribose, the bases and the rest of the inorganic acid combined together form a nucleotide. It is from the nucleotide sequences that the whole structure of the molecule as a whole is added up.

The unique is the order in which the organic bases will be located one after another and in relation to the neighboring chain. The nucleotide sequence is constructed according to certain principles, the main of which is complementarity (strict correspondence of purine and pyrimidine components). This allows each living creature to have its own genetic code, unique, innate and deeply specific.

Phenotypically, this manifests itself in the form of inheritance of completely different characteristics, in the fact that there are no two identical people (except for identical twins), distinctive features of appearance.

What kind of sugar does the DNA contain ?

The basis of any organic matter is the carbon chain of atoms. The DNA molecule was no exception. After all, the structure of DNA is sugar, namely it consists of a sequence of five carbon atoms, combined in a cyclic structure. The same molecule is interrupted by the oxygen bridge entering the general cycle.

The chemical composition of sugar is expressed by the following empirical formula: C ₅ H ₁₀ O ₄ . This molecule - aldopentose, which includes five carbon atoms, twisted into a cycle. In addition, one of the chain atoms instead of the hydroxyl group contains only hydrogen, so in the name of the sugar there was such a prefix as "deoxy", that is, without oxygen.

The chemical composition of sugar was discovered and investigated by Phibus Lieven, who discovered the entire structure and chemical nature of the compound in 1929.

Bases in the composition of the molecule

The organic bases that make up the nucleic acid of DNA can be divided into two main groups.

1. Purine - complex structures formed by two carbon cycles - five-membered and six-membered. These include adenine and guanine, which are complementary to pyrimidine bases in deoxyribonucleic acid.
2. Pyrimidine - six-membered carbon cycles. This includes thymine and cytosine.

Thus, it turns out that the DNA composition includes sugar and a base, connected to each other and bonded to the phosphoric acid radical . All this together and it turns out a nucleotide. In the double-stranded structure of the general DNA molecule, the nucleotides bind together according to the complementarity rule: adenine corresponds to the base thymine, and guanine corresponds to the cytosine.

Types of relationships between particles

The main types of connections between the component DNA structures are as follows:

• Hydrogen;
• Covalent polar;
• The forces of intermolecular attraction;
• Vaan der Waals interaction.

This allows the double-stranded structure to exist in three conformations:

• Primary - linear sequence of nucleotides;
• Secondary - spirally twisted each filament and both near each other;
• Tertiary - a complex conformational globule of a strongly helical molecule.

Thus, the fact that the structure of DNA includes sugar, bases and acid residues is the basis of its structure and soil for the implementation of a number of interactions and the formation of chemical bonds.

The importance of DNA for organisms

There are several important points:

1. The molecules of the acid under consideration are included in the chemical composition of the chromosomes, which determine the individuality of all living organisms.
2. DNA is the basis for the synthesis of complex polypeptide chains responsible for the coding and transmission of hereditary traits.
3. Deoxyribonucleic acid is the basis for transcription, that is, the primary synthesis of RNA, subsequently protein.

Such processes occur in all organisms. This allows us to call this structure a universal unit of all living things.

Molecular replication

This process is a doubling of the DNA molecule, proceeding spontaneously with the expenditure of energy in living organisms. The main component here is DNA polymerase, an enzyme that catalyzes and controls the entire synthesis.

The essence of replication is that each of the threads of the molecule is divided and doubled its linear sequences. As a result of the process, two new DNA molecules are formed, each containing one old polypeptide chain, and the second completely new, built according to the principle of complementarity.

The value of the process is to provide the offspring with genetic information in full.