huge variety of compounds of different chemical nature of man has managed to synthesize in the laboratory.However, still the most important and meaningful to the lives of all living systems have been and will remain is the natural, natural substances.That is, those molecules that are involved in thousands of biochemical reactions inside the organism and are responsible for the normal operation.
vast majority of them belongs to a group that has the name "biological polymers."
general notion of biopolymers
First, we should say that all of these compounds - High possessing mass reaching to millions of Daltons.These substances - animal and plant polymers, which play a decisive role in building the cells and their structures, maintenance metabolism, photosynthesis, respiration, nutrition and all other vital functions of any living organism.
overestimate the importance of these compounds difficult.Biopolymers - are natural substances of natural origin, formed in living organisms and which are the basis of all life on our planet.What exactly is the connection they include?
Biopolymers cells
them quite a lot.Thus, the main biopolymers are as follows:
- proteins;
- polysaccharides;
- nucleic acids (DNA and RNA).
Besides these, here it is possible to include many mixed polymers that are formed from combinations of those already listed.For example, lipoproteins, lipopolysaccharides, glycoproteins and others.
General properties
There are several features that are common to all of the molecule.For example, the following general properties of biopolymers:
- high molecular weight due to the formation of huge macrochains with ramifications in the chemical structure;
- types of bonds in macromolecules (hydrogen, ionic interactions, electrostatic attraction, disulfide bridges, peptide bonds, etc.);
- structural unit of each circuit - monomer unit;
- stereoregularity or lack thereof in the structure of chain.
But in general, all of biopolymers is still more differences in the structure and functions, rather than similarities.
Proteins
great importance in the life of all living beings are protein molecules.Such biopolymers - is the basis of the biomass.Even in the theory of Oparin-Haldane life on Earth originated from coacervate droplets, which is a protein.
structure of these substances is subject to a strict order in the structure.The basis of each protein comprise amino acid residues that can be connected together in a chain of unlimited length.This is done by forming special bonds - peptide.Such a bond is formed between the four elements: carbon, oxygen, nitrogen and hydrogen.
The structure of the protein molecule can include a lot of amino acid residues as the same or different (a few tens of thousands or more).Whole species of amino acids found in the composition of the compounds, there are 20. However, their combination allows a variety of proteins to flourish in number and species against.
Biopolymers proteins have different spatial conformation.For example, a representative may exist in the form of primary, secondary, tertiary or quaternary structure.
most simple and linear one - primary.It is simply the number of amino acid sequences joined together.
secondary conformation has a more complex structure, as the total macrochains helical protein begins to form coils.Two located near macrostructure held next to each other by covalent and hydrogen interactions between groups of atoms.There are alpha and beta-helix secondary structure of proteins.
tertiary structure is rolled into a ball of a macromolecule (polypeptide chain) protein.It is a complex network of interactions within this globule allows it to be fairly stable and keep the adopted form.
quaternary conformation - a several polypeptide chains, helically coiled and twisted into a ball, which while still interconnected to form multiple links of various types.The most difficult globular structure.
functions of protein molecules
- Transportation.It is carried out a part of the cell plasma membrane proteins.They form ion channels that are able to pass certain molecules.Also, many proteins are part of the movement of organelles of protozoa and bacteria, so directly participate in their movement.
- Energy function executes data very active molecules.One gram of protein metabolism constitutes 17.6 kJ.Therefore, the consumption of plant and animal products containing these compounds, it is vital to living organisms.Construction
- function is to participate in protein molecules constructing the majority of cellular structures, own cells, tissues, organs, and so on.Virtually any cell is basically constructed from these molecules (cytoplasm cytoskeleton, plasma membrane, ribosome, mitochondria and other structures are involved in the formation of protein compounds).
- catalytic function is carried out by enzymes, which in their chemical nature are nothing other than proteins.Without enzymes it would be impossible most biochemical reactions in the body, as they are - biological catalysts in living systems.
- Receptor (also signal) function helps cells to navigate and respond to any changes in the environment, both mechanical and chemical.
If we look at proteins in greater depth, it is possible to allocate some more secondary functions.However listed are basic.
nucleic acid
Such biopolymers - is an important part of every cell, whether it is prokaryotic or eukaryotic.Because nucleic acids are molecules of DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), each of which is a very important element for the living beings.
By their chemical nature of DNA and RNA sequence are nucleotides linked by hydrogen bonds and the phosphate bridges.The structure consists of DNA nucleotides, such as:
- adenine;
- thymine;
- guanine;
- cytosine;
- pyatiuglerodisty sugar deoxyribose.
RNA characterized in that thymine is replaced with uracil, and the sugar - ribose.
Due to the special structural organization of the DNA molecule can perform a number of vitally important functions.RNA also plays a big role in the cell.
functions such acids
nucleic acids - biopolymers, are responsible for the following functions:
- DNA is the custodian and transmitter of genetic information in the cells of living organisms.In prokaryotes, this molecule is distributed in the cytoplasm.The eukaryotic cell is inside the nucleus, separated karyotheca.
- double-stranded DNA molecule is divided into portions - the genes that make up the structure of chromosomes.The genes of every creature form a special genetic code, which is encrypted all the signs of the organism.
- RNA is of three kinds - matrix, ribosomal and transport.Ribosomal involved in the synthesis and assembly of protein molecules on the corresponding structures.Matrix and transport transfer information read from the DNA and decipher its biological significance.
polysaccharides
These compounds - is mostly vegetable polymers, that is found precisely in the cells of flora.Particularly rich in polysaccharides of the cell wall that contains cellulose.
By their chemical nature, polysaccharides - a macromolecule carbohydrate complex structure.Can be linear, layered, cross-linked conformations.Monomers act simple five-, often six-carbon sugars - ribose, glucose, fructose.They are of great importance for living beings, as part of the cell is a replacement plant nutrients are split to release large amounts of energy.
value different representatives
very important biological polymers such as starch, cellulose, inulin, glycogen, chitin and others.That they are important sources of energy in living organisms.
example, cellulose - a mandatory component of the cell wall of plants, some bacteria.It gives strength, a certain form.In industry, a man used to produce paper, securities acetate fibers.
Starch - spare plant nutrient, which is also a valuable food product for humans and animals.
glycogen, or animal fat, - reserve nutrients in animals and humans.Performs functions of thermal insulation, energy source, mechanical protection.
mixed biopolymers as a part of living beings
addition to those that we have considered, there are various combinations of high-molecular compounds.Such biopolymers - a mixed complex structure of proteins and lipids (lipoprotein) or of polysaccharides and proteins (glycoproteins).It is also possible the combination of lipids and polysaccharides (lipopolysaccharide).
Each of these biopolymers has many varieties performing in living beings a number of important functions: transport, signaling, receptor, regulatory, enzymatic, construction and many others.Their structure is chemically very complex and not all representatives deciphered, so the function is not fully defined.At present, it is known only to the most common, but much of the frontiers of human knowledge.
