Biomolecules refer to all kinds of molecules peculiar to living organisms. They are all organic matter. Typical cells contain 10,000 to 100,000 kinds of biomolecules, of which nearly half are small molecules, and the molecular weight is generally below 500.
The rest are polymers of small biomolecules with a large molecular weight. Generally, more than 10,000, and some as high as 100,000 so they are called Biomacromolecules. The small molecular units that make up biological macromolecules are called Building blocks. Amino acids, nucleotides, and mono-saccharides are the building blocks of proteins, nucleic acids, and polysaccharides, respectively.
Biomolecules have their own unique structures. Biological macromolecules have a large molecular weight, a large number of components, a large number, and an ever-changing arrangement sequence, so their structures are very complex.
It is estimated that there are 10-10 types of protein alone. Biomolecules are in order. Each biomolecule has its own structural characteristics. All biomolecules exist in the life system with a certain order (organization).
Biological macromolecules (biomacromolecule) and a low relative molecular biological organic compared to an organic compound having a high relative molecular weight higher substance groups. They are multimolecular systems formed by the polymerization of organic compounds of low relative molecular weight.
Most of the biological macromolecules are formed by the aggregation of simple composition structures. The constituent units of proteins are amino acids and the constituent units of nucleic acids are nucleotides … Amino acids and fatty acids are called biological single molecules, which are closely related to life. They are the basic substances that makeup macromolecules.
In terms of chemical structure, proteins are formed by dehydration condensation of α-L- amino acids, and nucleic acids are formed by dehydration condensation of purine and pyrimidine bases with sugar D- ribose or 2- deoxy -D-ribose and phosphate. Polysaccharides It is made by dehydration and condensation of monosaccharide.
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From this, it can be seen that the chemical reactions that change from bio-organic compounds with low relative molecular weight to bio-organic compounds with high relative molecular weight are all dehydration condensation reactions. It refers to organic molecules with molecular weights of tens of thousands or more as the main active ingredient in the body.
High relative molecular weight Bio-organic compounds (biomacromolecules) mainly refer to proteins, nucleic acids, and high-molecular-weight hydrocarbons.
Common biological macromolecules include proteins, nucleic acids, and polysaccharides. This definition is only conceptual, opposite biomacromolecule is a small molecule material (carbon dioxide, methane, etc.) and inorganic matter.
In fact, biological macromolecules are characterized by their various biological activities and their role in biological metabolism. Biological macromolecules are the basic substances that makeup life. For example, the molecular weight of certain peptides and certain lipids has not reached an astonishing level, but it also shows important physiological activities in the process of life.
Formation of biological Macromolecules
In primitive Earth conditions, there are two paths to achieve dehydration condensation to form a polymer, one is by heating, the low relative molecular mass and dehydrating and heating the polymeric material constituting, the other is the use of the presence on primitive earth dehydration Agent to condense. The former is often performed in a near-water volcanic environment, while the latter can be performed in a water environment.
Biological macromolecules are synthesized in vivo by a simple structure, it can be decomposed through decomposition in a living body as a simple structure, usually during the synthesis consumes energy, released during decomposition energy.
Biological macromolecules are important constituents of organisms. They not only have biological functions but also have large molecular weights and complex structures. In addition to the main proteins and nucleic acids in biological macromolecules, there are also sugars, lipids and their combined products.
Such as glycoprotein, lipoprotein, nuclear protein and so on. Their molecular weight is often a hundred times or a thousand times greater than that of general inorganic salts. The molecular weight of proteins ranges from 10,000 to tens of thousands, and the molecular weight of nucleic acids can reach millions.
The complex structure of these biological macromolecules determines their special properties, and their movements and changes in the body reflect important life functions. Such as metabolism to supply the energy and materials needed to sustain life, transfer genetic information, control embryo differentiation, promote growth and development, and generate immune functions.
Human research on biological macromolecules has gone through a long history of nearly two centuries. Due to the complex structure of biological macromolecules and their susceptibility to denaturation due to temperature, acid, and alkali, it brings great difficulties to research. Before the end of the 20th century, the main research work was the extraction, properties, chemical composition and preliminary structural analysis of biological macromolecular substances.
Early Research Results
Since the 1830s, when the cytology was established, some people have studied proteins. The naming of proteins began in 1836. At that time, the famous Swedish chemist J. Berzelius and the Dutch chemist G. Mulder who was studying egg protein compounds proposed the use of “proteins”.
Name such compounds. And listed it as the most important substance in the living system. By the beginning of this century, 12 kinds of 20 amino acids that make up proteins have been discovered, and the remaining amino acids have been discovered in 1940. At the end of the 19th century, organic chemists began to explore the structure of proteins.
German organic chemist Fisher (E. Fischer ) cooperated with others to put forward the argument that peptide bonds between amino acids are connected to form proteins. In 1907, Fisher synthesized a 15 glycine and 3 leucine Consists of a long chain of 18 peptides.
At the same time, Bernard (J.D. Bernal) and Astbury (W.T. Astbury) in the British crystal analysis school have used X-ray diffraction analysis to analyze the structure of proteins such as wool and hair, which prove that they are folded Curly fibrous substance. With the deepening of research, scientists have figured out that protein is the main component of muscle, blood, hair and so on, and has multiple functions.
Discovery of nucleic acids
Nucleic acids were discovered much later than proteins. A 24-year-old Swiss chemist, F. Miescher, who worked in Germany in 1868, extracted what was then called “nuclear material” from a patient’s wound pus cells.
This was the earliest discovery of nucleic acids later recognized. Later Ke Saier (A.Kssel) and two of his students Jones (W.Jones) and Levine (P.A.Levene) understand the basic nucleic acid chemical structure confirmed nucleic acid is composed of many nucleotide composition Macromolecule.
Nucleotides are made up of bases, ribose, and phosphate. There are 4 types of bases (adenine, guanine, cytosine, and thymine), and 2 types of ribose (ie, ribose and deoxyribose). According to this, nucleic acids are divided into two categories: Ribonucleic Acid (RNA) and Deoxyribonucleic Acid (DNA).
According to a rough analysis, they believed that the amounts of the four bases in the nucleic acid were equal. Thus incorrectly deduced that the basic structure of the nucleic acid is that four nucleotides with different bases are connected into a tetranucleotide.
Based on the polymerization of nucleic acids, this is the more famous “four-nucleotide hypothesis”. This hypothesis has dominated the study of nucleic acid structure for more than 20 years since the 1920s and has played a considerable obstacle to understanding complex nucleic acid structures and functions.
Although nucleic acid was found in the nucleus at that time because its structure is too simple. It is difficult to imagine what role it can play in abnormally complicated genetic changes. Some scientists even thought that after the structure of the protein was clarified at that time. It was likely that the protein played a major role in heredity.
Clarification of enzymes
The elaboration of the enzyme began in 1897 when the German chemist E. Buchner extracted fermented yeast cells from ground yeast cells to ferment alcohol. According to Buschner’s research, enzymes extracted from the living body can work just as well.
It not only hit the popular theory of vitality at that time but also brought biochemical research into the stage of understanding chemical changes in cells. Later, the British biochemist Harden (A. Harden) and much other research on the specific chemical steps of alcohol fermentation.
In the 1920s, a large number of experimental results showed that the two processes of yeast fermenting sugar to produce alcohol and muscle contracting to turn sugar into lactic acid are basically the same, also known as glycolysis.
By the research of many scientists in the 1930s, and finally integrated by German biochemist H.A. Krebs, a tricarboxylic acid cycle in which CO2 and H2O and energy (ATP) were finally produced by biological respiration was proposed. During this period, many scientists studied the metabolism of fats and amino acids, as well as the mutual conversion of sugars, fats, and proteins in metabolism and their biosynthesis.
These processes are all catalyzed by enzymes.
The role of inorganic substances and biological macromolecules
The role of inorganic substances and biological macromolecules is mainly reflected in the role of metal ions and their complexes with biological macromolecules.
It mainly includes the probe and recognition of metal ions to biological macromolecules, the competition between ligands and biological macromolecules to metal ions, and the transfer of ions and electrons within or between biological macromolecules.
When metal ions are combined with biological macromolecules, obvious biochemical effects often occur.
For example, some metal chlorides and gluconates can activate and inhibit glucose oxidase activity. The role of metal ions and their complexes with proteins mainly includes conformational changes caused by metal binding, subsequent biological effects caused by association and assembly.
The study of metal ions and their interaction with DNA can help people understand the nature of life phenomena at the molecular level, and provide theoretical guidance for the rational design and search for effective therapeutic drugs.
Such as the interaction of small molecular transition metal complexes with large molecular DNA can explore the structure, mechanism and function of large molecular DNA.