The particularly significant past events in biochemistry have been concerned with placing biological phenomena on firm chemical foundations.<\/p>\n\n\n\n
Before chemistry could contribute adequately to medicine and agriculture, however, it had to free itself from immediate practical demands in order to become a pure science. This happened in the period from about 1650 to 1780, starting with the work of\u00a0Robert Boyle\u00a0and culminating in that of\u00a0Antoine-Laurent Lavoisier, the father of modern chemistry. Boyle questioned the basis of the chemical theory of his day and taught that the proper object of chemistry was to determine the\u00a0composition\u00a0of substances. His contemporary\u00a0John Mayow\u00a0observed the fundamental\u00a0analogy\u00a0between the respiration of an animal and the burning, or oxidation, of organic matter in air. Then, when Lavoisier carried out his fundamental studies on chemical oxidation, grasping the true nature of the process, he also showed, quantitatively, the similarity between chemical oxidation and the respiratory process. Photosynthesis was another biological phenomenon that occupied the attention of the chemists of the late 18th century. The demonstration, through the combined work of\u00a0Joseph Priestley,\u00a0Jan Ingenhousz, and\u00a0Jean Senebier, that photosynthesis is essentially the reverse of respiration was a milestone in the development of biochemical thought.Britannica QuizBiology Bonanza<\/p>\n\n\n\n
In spite of these early fundamental discoveries, rapid progress in biochemistry had to wait upon the development of structural\u00a0organic chemistry, one of the great achievements of 19th-century science. A living organism contains many thousands of different chemical\u00a0compounds. The elucidation of the chemical transformations undergone by these compounds within the living cell is a central problem of biochemistry. Clearly, the determination of the molecular structure of the organic substances present in living cells had to precede the study of the cellular mechanisms, whereby these substances are synthesized and degraded.<\/p>\n\n\n\n
There are few sharp boundaries in science, and the boundaries between organic and physical chemistry, on the one hand, and biochemistry, on the other, have always shown much overlap. Biochemistry has borrowed the methods and theories of organic and physical chemistry and applied them to physiological problems. Progress in this path was at first impeded by a stubborn misconception in scientific thinking\u2014the error of supposing that the transformations undergone by matter in the living organism were not subject to the chemical and physical laws that applied to inanimate substances and that consequently these \u201cvital\u201d phenomena could not be described in ordinary chemical or physical terms. Such an attitude was taken by the\u00a0vitalists, who maintained that natural products formed by living organisms could never be synthesized by ordinary chemical means. The first laboratory synthesis of an\u00a0organic compound,\u00a0urea, by\u00a0Friedrich W\u00f6hler\u00a0in 1828, was a blow to the vitalists but not a decisive one. They retreated to new lines of defense, arguing that urea was only an excretory substance\u2014a product of breakdown and not of synthesis. The success of the organic chemists in synthesizing many natural products forced further retreats of the vitalists. It is\u00a0axiomatic\u00a0in modern biochemistry that the chemical laws that apply to inanimate materials are equally valid within the living cell.<\/p>\n\n\n\n
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At the same time that progress was being impeded by a misplaced kind of reverence for living phenomena, the practical needs of man operated to spur the progress of the new science. As organic and physical chemistry erected an imposing body of theory in the 19th century, the needs of the physician, the pharmacist, and the agriculturalist provided an ever-present stimulus for the application of the new discoveries of chemistry to various urgent practical problems.<\/p>\n\n\n\n
Two outstanding figures of the 19th century, Justus von\u00a0Liebig\u00a0and\u00a0Louis Pasteur, were particularly responsible for dramatizing the successful application of chemistry to the study of\u00a0biology. Liebig studied chemistry in Paris and carried back to Germany the inspiration gained by contact with the former students and colleagues of Lavoisier. He established at Giessen a great teaching and research laboratory, one of the first of its kind, which drew students from all over Europe.<\/p>\n\n\n\n
Besides putting the study of organic chemistry on a firm basis, Liebig engaged in\u00a0extensive\u00a0literary activity, attracting the attention of all scientists to organic chemistry and popularizing it for the layman as well. His classic works, published in the 1840s, had a profound influence on contemporary thought. Liebig described the great chemical cycles in nature. He pointed out that animals would disappear from the face of the Earth if it were not for the photosynthesizing plants, since animals require for their nutrition the complex organic compounds that can be synthesized only by plants. The animal excretions and the animal body after death are also converted by a process of decay to simple products that can be re-utilized only by plants.<\/p>\n\n\n\n
In contrast with animals, green plants require for their growth only\u00a0carbon dioxide,\u00a0water, mineral salts, and sunlight. The minerals must be obtained from the\u00a0soil, and the fertility of the soil depends on its ability to\u00a0furnish\u00a0the plants with these essential nutrients. But the soil is depleted of these materials by the removal of successive crops; hence the need for fertilizers. Liebig pointed out that\u00a0chemical analysis\u00a0of plants could serve as a guide to the substances that should be present in fertilizers.\u00a0Agricultural chemistry\u00a0as an applied science was thus born.<\/p>\n\n\n\n
In his analysis of fermentation, putrefaction, and\u00a0infectious disease, Liebig was less fortunate. He admitted the similarity of these phenomena but refused to admit that living organisms might function as the causative agents. It remained for Pasteur to clarify that matter. In the 1860s Pasteur proved that various yeasts and bacteria were responsible for \u201cferments,\u201d substances that caused\u00a0fermentation\u00a0and, in some cases, disease. He also demonstrated the usefulness of chemical methods in studying these tiny organisms and was the founder of what came to be called\u00a0bacteriology.<\/p>\n\n\n\n
Later, in 1877, Pasteur\u2019s ferments were\u00a0designated\u00a0as enzymes, and, in 1897, the German chemist\u00a0E. Buchner\u00a0clearly showed that\u00a0fermentation\u00a0could occur in a press juice of\u00a0yeast, devoid of living cells. Thus a life process of cells was reduced by analysis to a nonliving system of enzymes. The chemical nature of enzymes remained obscure until 1926, when the first pure crystalline\u00a0enzyme\u00a0(urease) was isolated. This enzyme and many others subsequently isolated proved to be\u00a0proteins, which had already been recognized as high-molecular-weight chains of subunits called amino acids.<\/p>\n\n\n\n
The mystery of how minute amounts of dietary substances known as the\u00a0vitamins\u00a0prevent diseases such as beriberi, scurvy, and pellagra became clear in 1935, when\u00a0riboflavin\u00a0(vitamin B2<\/sub>) was found to be an\u00a0integral\u00a0part of an enzyme. Subsequent work has\u00a0substantiated\u00a0the concept that many vitamins are essential in the chemical reactions of the cell by virtue of their role in enzymes.<\/p>\n\n\n\n In 1929 the substance\u00a0adenosine triphosphate\u00a0(ATP) was isolated from muscle. Subsequent work demonstrated that the production of ATP was associated with respiratory (oxidative) processes in the cell. In 1940\u00a0F.A. Lipmann\u00a0proposed that ATP is the common form of energy exchange in many cells, a concept now thoroughly documented. ATP has been shown also to be a primary energy source for muscular contraction.<\/p>\n\n\n\n The use of\u00a0radioactive isotopes\u00a0of chemical elements to trace the pathway of substances in the animal body was initiated in 1935 by two U.S. chemists,\u00a0R. Schoenheimer\u00a0and\u00a0D. Rittenberg. That technique provided one of the single most important tools for investigating the complex chemical changes that occur in life processes. At about the same time, other workers localized the sites of metabolic reactions by ingenious technical advances in the studies of organs,\u00a0tissue\u00a0slices, cell mixtures, individual cells, and, finally, individual cell\u00a0constituents, such as nuclei,\u00a0mitochondria,\u00a0ribosomes,\u00a0lysosomes, and membranes.<\/p>\n\n\n\n In 1869 a substance was isolated from the nuclei of pus cells and was called\u00a0nucleic acid, which later proved to be\u00a0deoxyribonucleic acid\u00a0(DNA), but it was not until 1944 that the significance of DNA as genetic material was revealed, when bacterial DNA was shown to change the genetic matter of other bacterial cells. Within a decade of that discovery, the\u00a0double helix\u00a0structure of DNA was proposed by\u00a0Watson\u00a0and\u00a0Crick, providing a firm basis for understanding how DNA is involved in\u00a0cell division\u00a0and in maintaining genetic characteristics.<\/p>\n\n\n\n Advances have continued since that time, with such landmark events as the first\u00a0chemical synthesis\u00a0of a\u00a0protein, the detailed mapping of the arrangement of atoms in some enzymes, and the elucidation of\u00a0intricate\u00a0mechanisms of metabolic regulation, including the molecular action of hormones.<\/p>\n","protected":false},"excerpt":{"rendered":" The particularly significant past events in biochemistry have been concerned with placing biological phenomena on firm chemical foundations. Before chemistry could contribute adequately to medicine and agriculture, however, it had to free itself from immediate practical demands in order to become a pure science. This happened in the period from about 1650 to 1780, starting […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[12],"tags":[],"class_list":["post-2036","post","type-post","status-publish","format-standard","hentry","category-biochemistry"],"Cooking_time":"","jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/cake.appscodestudio.com\/index.php\/wp-json\/wp\/v2\/posts\/2036","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cake.appscodestudio.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/cake.appscodestudio.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/cake.appscodestudio.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/cake.appscodestudio.com\/index.php\/wp-json\/wp\/v2\/comments?post=2036"}],"version-history":[{"count":1,"href":"https:\/\/cake.appscodestudio.com\/index.php\/wp-json\/wp\/v2\/posts\/2036\/revisions"}],"predecessor-version":[{"id":2037,"href":"https:\/\/cake.appscodestudio.com\/index.php\/wp-json\/wp\/v2\/posts\/2036\/revisions\/2037"}],"wp:attachment":[{"href":"https:\/\/cake.appscodestudio.com\/index.php\/wp-json\/wp\/v2\/media?parent=2036"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cake.appscodestudio.com\/index.php\/wp-json\/wp\/v2\/categories?post=2036"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cake.appscodestudio.com\/index.php\/wp-json\/wp\/v2\/tags?post=2036"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}