Course Introduction: |
‘Molecules of Life’ course is one of the chemistry elective courses for Bachelor of Science General programme (BSCG) under the Choice Based Credit System (CBCS) of University Grants Commission (UGC). It is a four credits course and designed for students having a fair background knowledge of chemistry and biology. The concepts dealt with, in this course, are presented in a simple, easily understandable manner. This course aims to give the students an overall view of the essential features of molecules of life. From your previous knowledge you might be very well aware that carbohydrates, proteins, lipids, enzymes and nucleic acids constitute the important molecules for all the living system on earth. Therefore, these are called the molecules of life. The course deals with understanding and exploiting the chemical similarities as well as the differences, of living organisms. It attempts to correlate the chemical structure with biochemical functions. It has been established by biochemical studies that cell is the fundamental unit of all living systems and a universal feature of all the cells is that they contain many common chemical constituents, follow common metabolic pathways and have common mechanisms of cellular regulation. We can illustrate the above statement by pointing out that most of the living organisms contain twenty α-amino acids, which constitute the vast variety of proteins in them. Similarly, the membranes of different cells have a uniform basic phospholipid composition and organisation. Another example we can cite here is that of enzymes, which have an overall similarity in chemical structure and function. Also, various metabolic pathways associated with the biosynthesis and degradation of many biomolecules, such as carbohydrates, lipids, proteins and nucleic acids, are similar. Each of these biomolecules possesses a separate chemical nature, which suits for the functions it performs in the cell. There is an immense diversity of the organic molecules present in different living systems. However, all the large organic molecules, i.e., macromolecules are composed of rather small, simple but different molecules, which are better known as building blocks. For example, proteins are composed of α-amino acids and nucleic acids are polymeric chains of nucleotides. These basic building blocks of all organisms are similar in chemical nature. Our aim in introducing this course is to give you an exposure of these building blocks, and then tell you about their metabolism and biosynthesis. This course consists of four blocks. In Block-1, titled, ‘Cell Structure and Carbohydrates’ the fundamental unit of an organism viz., the cell has been described from structure and function points of view. The cell contains many common structural components which are functionally similar. It is because of this, that the cell structure and functions can be generalised. You may wonder as to why the cell structure and its functions are presented in this course. This is because all the biochemical reactions and transformations that sustain life, take place within the chemical environment as well as the physical limits of a cell. This is remarkable. This block also deals with the chemistry and biological significance of mcarbohydrates as important energy providing molecules. Block 2, ‘Amino Acids, Peptides and Proteins’ deals with proteins as the most complex biomolecules present in the cell and composed of amino acids. The chemical and structural organisation of proteins has been described after explaining the structure and nomenclature of the constituent molecules viz., amino acids and peptides. The understanding of the structure and function of proteins makes it easier for you to understand their functions as enzymes, which are biocatalysts. The last block, Block 5, ‘Bioenergetics and Metabolism’ of the course finally deals with the metabolism of the biomolecules responsible for providing energy to the living systems. A good background of the energetics of biological systems is given prior to describing the biochemical reactions involved in the common metabolic pathways. |