General purpose of this lecture is to present on Organic Compounds of Life. Living organisms have to be able to: Exchange matter and energy with their surroundings and Transform matter and energy into different forms. All of these changes are due to large organic compounds called macromolecules. A macromolecule is a combination of many smaller similar molecules polymerized into a chain structure. In living organisms there are three main types of macromolecules which control all activities and determine what an organism will do and become.