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Lesson 1 : Introduction to Biochemistry

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Biotechnology, Bioluminescence, Molecular Chemistry, Enzymatic Chemistry, Biogenetics, Genetic engineering, Pharmaceuticals, Endocrinology, Cytology, Hematology, Nutrition and Photosynthesis.

The term biochemistry is synonymous with two terms: physiological chemistry and biological chemistry. Those aspects of biochemistry that deal with the chemistry and function of very large molecules (e.g., proteins and nucleic acids) are often grouped under the term molecular biology. Biochemistry is a young science, having been known under that term only since about 1900. Its origins, however, can be traced much further back; its early history is part of the early history of both physiology and chemistry.

A living organism contains many thousands of different chemical compounds. 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. Biochemistry has borrowed the methods and theories of organic and physical chemistry and applied them to physiological problems

Two outstanding figures of the 19th century, Justus von Liebig and Louis Pasteur, were particularly responsible for dramatizing the successful application of chemistry to the study of biology. 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.

The mystery of how minute amounts of dietary substances known as the vitamins prevent diseases such as beriberi, scurvy, and pellagra became clear in 1935, when riboflavin (vitamin B2) was found to be an integral part of an enzyme. Subsequent work has substantiated the concept that many vitamins are essential in the chemical reactions of the cell by virtue of their role in enzymes.

In 1929 the substance adenosine triphosphate (ATP) was isolated from muscle. Subsequent work demonstrated that the production of ATP was associated with respiratory (oxidative) processes in the cell. In 1940 F.A. Lipmann proposed 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.

In 1869 a substance was isolated from the nuclei of pus cells and was called nucleic acid, which later proved to be deoxyribonucleic acid (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 double helix structure of DNA was proposed by Watson and Crick, providing a firm basis for understanding how DNA is involved in cell division and in maintaining genetic characteristics

Last modified: Monday, 16 January 2012, 6:47 AM