Biopolymers are ... Plant polymers

A huge number of various compounds of 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, there are and will remain exactly 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."

General concept of biopolymers

First of all, it should be said that all these compounds are high-molecular, having a mass reaching up to millions of Daltons. These substances are animal and vegetable polymers that 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 are the specific connections to them?

Biopolymers of a cell

There are a lot of them. So, the main biopolymers are the following:

• Proteins;
• Polysaccharides;
• Nucleic acids (DNA and RNA).

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.

Common Properties

We can distinguish several features that are inherent in all the molecules under consideration. For example, the following general properties of biopolymers:

• A large molecular mass due to the formation of huge macrochains with branching in the chemical structure;
• Types of bonds in macromolecules (hydrogen, ionic interactions, electrostatic attraction, disulfide bridges, peptide bonds, etc.);
• The structural unit of each chain is a monomer unit;
• Stereoregularity or its absence in the structure of the chain.

But in general, all biopolymers still have more differences in structure and functions than similarities.

Proteins

Protein molecules have immense importance in the life of any living things. Such biopolymers are the basis of the whole biomass. After all, even according to Oparin-Haldane theory, life on Earth originated from a coacervate droplet, which was a protein.

The structure of these substances obeys strict order in the structure. The basis of each protein is the amino acid residues, which are able to connect to each other in 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 a lot of amino acid residues, both identical and different (several tens of thousands and more). The total number of amino acids found in these compounds is 20. However, their diverse combination allows the protein to flourish quantitatively and species-wise.

Biopolymers of proteins have different spatial conformation. Thus, each representative can exist in the form of 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 distinguished by a more complex structure, since the total macrochain of the protein begins to coalesce, 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 coiled one macromolecule (a polypeptide chain) of a protein. A very complex network of interactions within a given globule allows it to be sufficiently stable and keep the accepted form.

A quaternary conformation is a set of polypeptide chains, coiled and twisted into a ball, which also form multiple bonds of different types. The most complex globular structure.

Functions of protein molecules

1. Transport. It is carried out by the protein cells that make up the plasma membrane. It is they that form the ion channels through which these or other molecules can pass. Also, many proteins are part of organoids of the movement of protozoa and bacteria, so they take a direct part in their movement.
2. The energy function is performed very actively by these molecules. One gram of protein in the process of metabolism forms 17.6 kJ of energy. Therefore, the consumption of plant and animal products containing these compounds is vital for living organisms.
3. The building function is the participation of protein molecules in the construction of most cellular structures, the cells themselves, tissues, organs, and so on. Almost any cell is based on these molecules (cytoskeleton of the cytoplasm, plasma membrane, ribosome, mitochondria and other structures are involved in the formation of protein compounds).
4. The catalytic function is carried out by enzymes, which by their chemical nature are nothing more than proteins. Without enzymes, it would be impossible for most biochemical reactions in the body, since they are biological catalysts in living systems.
5. Receptor (also signal) function helps the cells to orient themselves and react to any changes in the environment, both mechanical and chemical.

If we consider proteins in more depth, we can identify some secondary functions. However, the listed are the main ones.

Nucleic acids

Such biopolymers are an important part of every cell, be it prokaryotic or eukaryotic. After all, the nucleic acids are 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 nucleotide sequences linked by hydrogen bonds and phosphate bridges. The DNA composition includes such nucleotides as:

• Adenine;
• Thymine;
• Guanine;
• Cytosine;
• Five-carbon sugar deoxyribose.

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.

The functions of such acids

Nucleic acids are biopolymers responsible for the following functions:

1. DNA is the keeper and transmitter of genetic information in the cells of living organisms. In prokaryotes this molecule is distributed in the cytoplasm. In the eukaryotic cell is located inside the nucleus, separated by a karyolemma.
2. The double-stranded DNA molecule is divided into sections - the genes that make up the structures of the chromosome. The genes of each creature form a special genetic code, in which all the signs of the organism are encrypted.
3. RNA is of three types - matrix, ribosomal and transport. Ribosomal takes part in the synthesis and assembly of protein molecules on the appropriate structures. Matrix and transport carry information read from DNA and decipher its biological meaning.

Polysaccharides

These compounds are predominantly plant 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.

In their chemical nature, polysaccharides are macromolecules of complex carbohydrates. 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.

The importance of different representatives

Very important are biological polymers such as starch, cellulose, inulin, glycogen, chitin and others. They are the important sources of energy in living organisms.

So, cellulose is an obligatory component of the cell wall 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.

Mixed biopolymers in the composition of living beings

In addition to those that we have examined, there are also various 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 many varieties 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. Today, only the most common are known, but a significant part remains beyond the boundaries of human knowledge.