Animals are parasites.
Unlike bacteria and plants that are autotrophic , animals are heterotrophic , which means that while bacteria and plants are capable of constructing all the compounds they need from inorganic molecules and a source of energy, we cannot, and depend on them for our basic organic molecules. So we will not be considering the major pathways for initial synthesis, like photosynthesis. We will also not be considering the pathways for synthesis of fatty acids, or the details of carbohydrate synthesis. Next week we will cover synthesis of nucleic acids and proteins. Instead we will focus on degradation of molecules, particularly for release of energy.