Biochemistry is the study of the structure, composition, and chemical reactions of substances in living systems. It is the combination of biology with organic, inorganic and physical chemistry and the sciences of Molecular Biology, immunochemistry and neurochemistry. Its wide range of applications include research and development of medicine, use of chemical concepts, procedures, and techniques to study the diagnosis and therapy of disease, food sciences, dealing with the environmental problems on the chemical level etc. It is an interdisciplinary field of science and the major topics included under it are as follows:
The Molecular components of cells: Includes the study of the various molecules which show their presence and role in the living system.
Water- Polar, inorganic solvent with approximately 70-90 percent of weight of most forms of life. Water is regarded as one of the most important molecules of the cell and is an important determinant of the characteristic structure and biological properties of proteins and nucleic acids as well as membranes, ribosomes, and many other cell components.
Proteins- Proteins are the most abundant organic molecules in the cells, constituting 50 percent or more of their dry weight. There are different types of proteins, each involved in specific biological function or cell structures. All contain carbon, hydrogen, nitrogen and oxygen and nearly all contain sulfur. α- amino acids are the monomer units of proteins. Proteins show 4 types of structures, primary, secondary, tertiary and quaternery structure according to their complexities. One of the major functions of proteins is their action as enzymes. Enzymes and their kinetics are also studied elaborately under biochemistry.
Carbohydrates- these are defined as the polyhydroxy aldehydes or ketones and their derivatives having an empirical formula (CH2O)n. Monosaccharides consist of single polyhydroxy aldehyde or ketone unit. The most abundant monosaccharide being is the six carbon D-glucose. Oligosaccharides contain two to ten monosaccharide units joined by glycosidic linkage. Polysaccharides contain many monosaccharide units joined in long linear or branched chains. They act mainly as the storage or structural elements in the body.
Lipids- lipids are water insoluble organic biomolecules that can be extracted from cells and tissues by nonpolar solvents, e.g., chloroform, ether, benzene. They have several important biological functions like serving as structural components of cell membranes, and as storage and transport forms of metabolic fuel. They are involved in cell recognition and tissue immunity. They are categorized as simple and complex lipids according to the absence or presence of fatty acids respectively. Fatty acids are characterized by long chain hydrocarbon with terminal carboxyl group. Simple lipids include terpenes, steroids and prostangalndins and some common complex lipids are acyl glycerols, phosphoglycerols, sphingolipids and waxes.
Nucleotides and nucleic acids- the nucleotides are the monomeric units of nucleic acids. Deoxyribonucleic acids (DNA) and Ribonucleic acids (RNA) are chain- like macro molecules that function in the storage and transfer of genetic information. Each nucleotide contains three characteristic components namely a nitrogenous heterocyclic base (either a purine or pyrimidine), a pentose sugar, and a molecule of phosphoric acid. The major purines include adenine and guanine and the main pyrimidines are thymine, cytosine and uracil.
Vitamins and coenzymes- Vitamins have been recognized as compounds that are essential to the health of humans and other vertebrates but cannot be synthesized by these animals and have to be obtained through the diet. They are divided in two classes water soluble (vitamin B and C) and fat soluble(vitamin A,D,E, and K).