 Welcome to the course on biochemistry. Biological macromolecules are the most intriguing molecules as they form an integral part of any living species and the interactions and reactions that take place are fundamental to all living beings. Biochemistry deals with the knowledge of these life processes and how the different macromolecules work together to produce the most fascinating of all things a living being that can eat, grow and procreate. This course is an introductory course that will focus on the basic concepts in biochemistry. It deals with an understanding of the biological macromolecules, proteins, carbohydrates, lipids and nucleic acids. We will look into the structure of the macromolecules and see how nature has designed them to work in the most efficient manner possible. The structure and functional roles of the macromolecules will be studied in addition to the fundamentals of enzyme chemistry, the kinetics, enzyme mechanisms, inhibition, structure and mechanism of action of different proteins. The course will also touch upon the basics of membrane transport and bio energetic principles. The biochemistry course has been uploaded as a lecture series in NPTEL but this structured form has been prepared with different modules. After the completion of each module there will be a discussion forum where your queries will be addressed and quizzes and assignments given. After completion of the course I hope you will have a clear perception of the three dimensional structure and properties of these biological macromolecules in relationship to their biological functions that are so important for life. Thank you.