Biochemistry is the science of biologically significant chemical elements of the body and biomolecules, as well as chemical processes (reactions) involving them, the ways and methods of regulating metabolism, and the energy supply of these processes. The sections of biochemistry are aimed at explaining biological processes at the molecular and cellular levels. As the name suggests, biochemistry is at the intersection of biology and chemistry. Synonyms are the terms: “Physiological chemistry” (sometimes as part of medical physiology), “biological chemistry”. Biochemistry refers to the practical experimental sciences, relies heavily on quantitative analysis, and often involves experiments based on hypotheses designed to answer specific biological questions, such as determining how a group of proteins catalyzes the synthesis of a complex biomolecule or why biological membranes have different physical properties depending on their chemical composition.
Biochemistry is a means of expressing concepts and phenomena not only in the field of fundamental biological science, but also in the field of clinical medicine. Biochemistry, study of the chemical basis of organisms in health and disease, designed to establish a link between molecular structure and biological function of the chemical components of living matter.
History of Biochemistry development
The birth of biochemistry is traditionally associated with the end of the XIX century, when chemists discovered that the cellular extracts of brewer’s yeast contain everything necessary for alcoholic fermentation. This meant that the processes associated with living organisms could be understood from the point of view of fundamental chemistry. During most of the 20th century, scientists made numerous discoveries in the field of cellular biochemistry that led to an understanding of the chemical basis of life. These advances included the description of the chemical structure and function of the main classes of biomolecules: nucleic acids, proteins, carbohydrates, and lipids. Moreover, thousands of metabolic reactions that characterized the molecular synthesis and degradation in the cells of microorganisms, plants and animals have been studied. The knowledge gained from these biochemical studies has been used to develop pharmaceuticals, medical diagnostic tests, and new industrial processes. The development of biochemistry was greatly accelerated in the 1970s, when recombinant DNA technologies were developed.
Modern biochemistry encompasses both organic and inorganic chemistry, as well as the fields of microbiology, genetics, molecular biology, cell biology, physiology, and computational biology.
The applied role of biochemistry
Biochemistry, along with genetics and cell biology, is a central discipline in the life sciences. Biochemistry provides the basic chemical principles that guide discoveries in medicine, agriculture, and pharmaceuticals. Understanding the chemical reactions in living cells at the molecular level, knowing how cells communicate with each other in a multicellular organism, has led to a dramatic increase in human life expectancy through improvements in healthcare, food production, and environmental science. Biochemistry is a powerful applied science that uses advanced experimental methods to develop” in vitro ” cellular processes and enzymatic reactions, for example, the development of new pharmaceuticals based on knowledge of biochemical processes in pathological conditions, the introduction of diagnostic tests that detect these disorders. Another example of the applied nature of biochemistry is improved detergents based on enzymatic reactions and faster maturation of fruits and vegetables using ethylene gas.
Moreover, environmental science has also benefited from advances in biochemistry by developing quantitative field tests that provide information about changes in fragile ecosystems due to industrial or biological pollution.
Hierarchy of complexity of the chemical organization of living systems
Speaking about the principles of biochemistry, there are several levels of biochemical hierarchy (organizational complexity). Biochemistry studies phenomena at all these levels.
Biochemistry-hierarchical organization of living systems
Hierarchical organization and chemical complexity of biological systems. Seven hierarchical levels, with examples of the complexity of the structures at these levels.
Chemical elements and functional groups
Chemical elements and functional groups in the human body
At the base, at the very bottom of this hierarchy, are the chemical elements and functional groups. The vast majority of elements in living organisms are hydrogen and oxygen (which make up water). Living organisms are characterized by an abundant content of carbon, the basis of organic molecules. Hydrogen, oxygen, carbon, nitrogen, phosphorus and sulfur, forming bonds with each other, are combined into functional groups that give certain properties to biomolecules. Most often, amino, hydroxyl, sulfhydryl, phosphoryl, carboxy, and methyl groups are present in biomolecules.
Biomolecules
At the next stage, chemical groups are organized into biomolecules-monomers, such as amino acids, nucleotides, simple sugars and fatty acids. Biomolecules-monomers serve mainly as building blocks for macromolecules-polymers. In addition, they can serve as signaling molecules for cells or neurotransmitters, play a role in energy storage and conversion, catalyze biochemical reactions, or have a structural function.
Macromolecules
Even higher-order structures include macromolecules (biomolecules — polymers), such as proteins (polymers of amino acids), nucleic acids (polymers of nucleotides), or polysaccharides, such as cellulose, amylose, and glycogen (polymers of sugars). The sequence of building blocks (for example, amino acids) provides important information for determining the overall structure of the molecule and its properties.
Metabolic pathways
The organization of macromolecules and enzymes into metabolic pathways is the next hierarchical level. These pathways allow cells to coordinate and control complex biochemical processes within them in response to energy needs or the availability of energy. Examples of metabolic pathways include: glucose metabolism (glycolysis and gluconeogenesis), energy conversion (citrate cycle or CPC), and fatty acid metabolism (fatty acid oxidation and biosynthesis).
At the next level, there are cells with their specialization, which allows multicellular organisms to exist in their environment. Thanks to the mechanisms of signal transmission, information is exchanged between cells.
Organisms
Organisms represent the next level, as they consist of a large number of specialized cells, which allows multicellular organisms to respond to environmental changes. Multicellular organisms are able to adapt to changes through signal transduction mechanisms that facilitate cell-to-cell communication. These mechanisms exist due to special membrane receptors, as well as the circulatory system in animals and its analogues in plants and other organisms.
The upper rung of the hierarchical ladder of life describes the complex interactions between organisms that occur in ecosystems. Organisms interact with their environment and with each other, and can have beneficial or harmful effects on life at the level of local or global ecosystems.
For example, aquatic environments are extremely sensitive to changes in ecosystem dynamics, as evidenced by the effects of algal blooms on fish populations. If a rapid increase in algae growth occurs in a limited area, such as a bay or lake, this can lead to a biochemical imbalance in the ecosystem as a result of increased decomposition of algae organic matter, and in some cases to acute depletion of oxygen reserves and mass death of fish. Harmful algal blooms occur when nutrient levels rise in the aquatic ecosystem, as well as when water temperature and sunlight are optimal for growth. Sudden changes that encourage algae blooms may occur naturally as a result of seasonal changes in environmental conditions, or may occur as a result of industrial emissions that directly increase the level of nitrogen or phosphate in the water. Understanding the environmental factors that contribute to algae blooms and finding safe ways to control them in sensitive aquatic environments requires understanding key biochemical processes at multiple levels of the ecosystem.