Biochemistry and Molecular Biology - Belyasova N.A. 2002

Introduction
A Brief Historical Outline of the Development of Biochemistry and Molecular Biology

As an independent science, biochemistry emerged by the mid-19th century, although the groundwork for its development was laid almost a century earlier. Notable milestones include J. Priestley's discovery (1770–1780) of oxygen absorption by animals and emission by plants; the Isolation of the first organic molecules from natural sources—glycerol, malic, citric, lactic, and uric acids (Scheele, Rouelle, 1770–1786); the elucidation of protein composition as nitrogen-containing substances (Dalton, 1803); the isolation of the first amino acid, asparagine, from asparagus (Asparagus) juice (Vauquelin, 1806); the derivation of the equation for Alcoholic Fermentation (Gay-Lussac, 1810); and the ISOLATION OF A crystalline fatty acid preparation from the acid Treatment of soap, alongside the discovery of Cholesterol (Chevreul, 1811, 1812).

Finally, in 1828, F. Wöhler synthesized the first organic compound—urea—from inorganic substances, delivering a crushing blow to vitalism. Many consider this achievement to be the primary milestone in the establishment of biochemistry as an independent science. In 1833, Payen and Persoz purified and studied The properties of the first enzyme molecule—wheat amylase—postulating The Central Role of Enzymes in biology. Between 1854 and 1864, Pasteur proved that fermentation is a function of living Cells (Yeast) and provided decisive arguments against the hypothesis of spontaneous generation. Concurrently, beginning with F. Miescher's Discovery of DNA (1869), the Chemistry of Nucleic acids was born.

By the late 19th century, a fierce debate erupted between Louis Pasteur and Justus von Liebig regarding The Nature of fermentation. Pasteur maintained that fermentation was a phenomenon that could occur exclusively within microbial cells, whereas Liebig held a different view, advocating for the Chemical Nature of the process—one, however, involving substances similar to the then-known amylase. The dispute was ultimately resolved by the Buchner brothers, who demonstrated in 1897 that fermentation could take place in Cell-free yeast extracts. Thus, it became clear that fermentation is a chemical process capable of occurring both inside and outside cells, driven by enzymes—the metabolic products of living organisms. As historians have noted: "...the appearance of gas bubbles in the Buchners' experiment marked the birth of modern biochemistry and enzymology."

Following this discovery, biochemistry received a powerful developmental impetus: in 1901–1902, Emil Fischer demonstrated that Proteins are Polypeptides and established the Nature of the peptide bond; in 1905, Knoop discovered the ß-Oxidation of Fatty acids; in 1911, Funk isolated crystalline thiamine and coined the term "vitamin"; in 1913, Michaelis and Menten developed the THEORETICAL FOUNDATIONS OF enzyme kinetics; in 1926, Sumner isolated crystalline urease and proved it to be a protein; in 1933, Krebs and Henseleit discovered and investigated the Chemistry of the Urea Cycle, while Embden and Meyerhof uncovered the most crucial features of Glycolysis and fermentation. Even this Brief Overview of the major achievements of biochemistry in the first half of the 20th century demonstrates that scientific interest had shifted toward deciphering the processes occurring within the living cell.

As a result, by the mid-20th century, the principal metabolic transformations within cells had been elucidated. These discoveries included Photosynthesis (K.A. Timiryazev), The Tricarboxylic Acid Cycle (H. Krebs), The process of Oxidative Phosphorylation, and the fundamental laws of cellular energy conversion.

During this period, biochemists were still unable to answer one of humanity's most pressing questions: which cellular substance carries hereditary information. Proteins had been studied more thoroughly than other macromolecules, revealing a startling diversity. It was logical to assume that protein molecules, being so compositionally variable, must serve as the material encoding the equally variable properties of living beings. However, as early as 1928, Griffith's experiments yielded the first evidence of Nucleic Acids participating in this process. Subsequently, in 1944, American scientists Avery, MacLeod, and McCarty proved that DNA is the substance responsible for the storage and transmission of hereditary information in cellular organisms.

The most advanced Methods available across various scientific disciplines were employed to investigate the Structure of Nucleic Acids. In particular, X-ray crystallography, the foundations of which were laid in 1934 by Bernal and Crowfoot, enabled researchers to approach The Study of the three-dimensional structure of DNA. Around this time, molecular biology emerged as an independent science. Warren Weaver, Director for the Natural Sciences at the Rockefeller Foundation, was the first to mention its inception. In his 1938 report, he noted that "in the border areas where physics and biology, or chemistry and biology, meet, there is beginning to be built up a new branch of science, molecular biology, which is beginning to uncover many secrets concerning the ultimate elements of the living cell."

Modern biochemistry is characterized by the integration of rapid automated methods for analyzing substances and processes. Today, automated control is applied to amino acid protein analysis, the quantification of mono- and Disaccharides in biological fluids, nucleic acid sequencing, peptide and oligonucleotide synthesis, and the chromatographic and gel-filtration Separation of natural compounds, among other techniques.

In concluding this overview of biochemical achievements, one may summarize that biochemistry studies the chemical Composition and Structure of living matter, as well as the chemical processes occurring within living organisms.

The "birth" date of molecular biology is considered to be 1953, when physicist Francis Crick and biologist James Watson elucidated The structure of DNA—The Double Helix. This remarkable discovery formed the basis for the majority of molecular biological research, underpinned by the aforementioned achievements of the "phage school" (Avery et al.) and physicists (Bernal, Crowfoot). Furthermore, the shift of biochemical focus toward the study of nucleic acids was facilitated by the formulation in 1941 by G. Beadle and E. Tatum of the "one Gene–one enzyme" hypothesis, which they deduced while studying biochemical Mutations in the bread mold Neurospora crassa.

A defining feature of molecular biology is the investigation of macromolecular structure and its relationship to function. This is most vividly demonstrated in the case of DNA. However, molecular biology also investigates other molecules, as evidenced by its major scientific achievements: the structure of certain proteins has been decoded and correlated with their Functions (M. Perutz, J. Kendrew, F. Sanger, C. Anfinsen, et al.); the structure and biological mechanisms of Nucleic Acids and Ribosomes have been determined (J. Watson, F. Crick, T. Caspersson, J. Brachet, S. Weiss, et al.); METABOLISM/28.html">The Genetic Code has been deciphered (M. Nirenberg, H. Khorana, S. Ochoa); the method of specific DNA Cleavage using Restriction Endonucleases—the foundation of modern Introduction/32.html">Genetic Engineering—has been developed (H. Smith, W. Arber, D. Nathans); The phenomenon of reverse Transcription has been discovered (H. Temin, D. Baltimore, S.M. Gershenzon); the mechanisms and stages of Protein Biosynthesis (F. Jacob, J. Monod, F. Crick) and nucleic acid synthesis (A. Kornberg, S. Ochoa) have been uncovered; viral structure and mechanisms of reproduction have been established, and Genetic engineering METHODS developed (P. Berg, W. Arber, H. Smith); techniques for introducing foreign DNA into various cells via vectors have been created (H. Boyer, S. Cohen, D. Helinski); gene synthesis has been accomplished (H. Khorana); the virus-genetic theory of Cancer has been proposed (L.A. Zilber); The nucleotide sequence in tRNA has been established (A.A. Baev); and the DNA Sequencing method has been developed (A. Maxam, W. Gilbert, F. Sanger).

Thus, molecular biology can be defined as the science that investigates the functioning of living organisms through the prism of the Chemical Structure of the molecules and atoms that comprise them.