A huge number of different compoundsa different chemical nature man managed to synthesize in laboratory conditions. However, all the same, the most important and significant for the life of all living systems were, is and will remain natural, natural substances. That is, those molecules that participate in thousands of biochemical reactions within organisms and are responsible for their normal functioning.
The vast majority of them belong to a group called "biological polymers."
First of all, it should be said that all thesecompounds - high molecular weight, having a mass of up to millions of Daltons. These substances are animal and vegetable polymers, which play a decisive role in the construction of cells and their structures, providing metabolism, photosynthesis, respiration, nutrition and all other vital functions of any living organism.
It is difficult to overestimate the importance of such compounds. Biopolymers are natural substances of natural origin, formed in living organisms and are the basis of all life on our planet. What exactly are the connections to them?
There are a lot of them. So, the main biopolymers are the following:
In addition to them, many mixed polymers formed from the combinations of the already listed are also included here. For example, lipoproteins, lipopolysaccharides, glycoproteins and others.
We can distinguish several features that are inherent in all the molecules under consideration. For example, the following general properties of biopolymers:
But in general, all biopolymers still have more differences in structure and functions than similarities.
Huge significance in the life of any living beingshave protein molecules. Such biopolymers are the basis of the whole biomass. After all, even according to the theory of Oparin-Haldane, life on Earth originated from a coacervate droplet, which was a protein.
The structure of these substances complies with strictorderliness in the structure. The basis of each protein is amino acid residues, which are able to connect with each other in an unlimited chain length. This occurs by the formation of special bonds - peptide bonds. Such a bond is formed between four elements: carbon, oxygen, nitrogen and hydrogen.
The composition of the protein molecule can include very muchamino acid residues, both the same and different (several tens of thousands or more). The total number of amino acids found in these compounds is 20. However, their diverse combination allows the protein to flourish in a quantitative and species-specific manner.
Biopolymers of proteins have different spatial conformation. Thus, each representative can exist as a primary, secondary, tertiary or quaternary structure.
The simplest and linear of them is the primary one. It is simply a series of amino acid sequences connected to each other.
Secondary conformation is more complicatedstructure, since the total macrochain of the protein begins to spiral, forming coils. Two nearby macrostructures are kept near each other due to covalent and hydrogen interactions between the groups of their atoms. There are alpha and beta-helices of the secondary structure of proteins.
The tertiary structure is a foldedin the tangle of one macromolecule (polypeptide chain) protein. A very complex network of interactions within a given globule allows it to be sufficiently stable and keep the accepted form.
Quaternary conformation is a fewpolypeptide chains, folded spirally and twisted into a ball, which in this case also form multiple bonds of different types among themselves. The most complex globular structure.
If we consider proteins in more depth, we can identify some secondary functions. However, the listed are the main ones.
Such biopolymers are an important part of eachcells, be it prokaryotic or eukaryotic. After all, nucleic acids include DNA molecules (deoxyribonucleic acid) and RNA (ribonucleic acid), each of which is a very important link for living things.
In their chemical nature, DNA and RNA are sequences of nucleotides linked by hydrogen bonds and phosphate bridges. The DNA composition includes such nucleotides as:
RNA differs in that thymine is replaced by uracil, and sugar - by ribose.
Due to a special structural organization, DNA molecules are capable of performing a number of vital functions. RNA also plays a large role in the cell.
Nucleic acids are biopolymers responsible for the following functions:
These compounds are predominantlyvegetable polymers, that is, they are found in the cells of the representatives of the flora. Particularly rich in polysaccharides is their cell wall, which contains cellulose.
By their chemical nature, polysaccharides aremacromolecule of carbohydrates of complex structure. They can be linear, layered, cross-linked conformations. Monomers are simple five-, more often six-carbon sugars - ribose, glucose, fructose. They are of great importance for living beings, since they are part of the cells, they are a reserve nutrient of plants, they are split with the release of a large amount of energy.
Biological polymers such as starch, cellulose, inulin, glycogen, chitin and others are very important. They are the important sources of energy in living organisms.
Thus, cellulose is an obligatory component of cellularwalls of plants, some bacteria. Gives strength, a certain form. In human industry, it is used to produce paper, valuable acetate fibers.
Starch is a reserve plant nutrient, which is also a valuable food product for humans and animals.
Glycogen, or animal fat, is a reserve nutrient for animals and humans. It performs the functions of thermal insulation, energy source, mechanical protection.
In addition to those that we have considered, there are alsovarious combinations of high-molecular compounds. Such biopolymers are complex mixed structures from proteins and lipids (lipoproteins) or from polysaccharides and proteins (glycoproteins). A combination of lipids and polysaccharides (lipopolysaccharides) is also possible.
Each of these biopolymers has a pluralityvarieties that perform in living beings a number of important functions: transport, signal, receptor, regulatory, enzymatic, construction and many others. Their structure is chemically very complex and far from deciphered for all representatives, therefore, the functions are not completely determined. For today only the most common are known, but a significant part remains beyond the boundaries of human knowledge.