2.1 - A - Carbon Compounds & Metabolism
Molecular biology is a branch of science that observes biological activities at the molecular level. It aims to explain living processes in terms of the chemical substances involved. Many molecules play an important role in organisms, from simple ones such as water to complex ones including nucleic acids and proteins.
Carbon is the base element for all organic compounds due to its ability to form multiple covalent bonds, which involves atoms sharing electrons. Since carbon has four valence electrons, it is able to bond with up to four atoms and can form single or double bonds. This allows for a diversity of carbon-based compounds to exist.
Atoms containing carbon can have complex structures, including rings or chains of any length. For example, fatty acids can contain chains of up to 20 C atoms. Below is a sample carbon chain.
Overall, organisms make use of four main types of carbon compounds. Each has a different structure, which affects the functions they can perform in the cell and organisms as a whole.
Together, these carbon macromolecules make up most of the structures of the cell as well as perform the necessary life functions.
Urea & Vitalism
Urea is a N-containing compound that is excreted in the urine when a large amount of amino acids are present in the body. It is produced in the deammonification of amino acids as a means of getting rid of nitrogen. It is made through a cycle of enzyme-catalyzed reactions in the liver.
Urea can also be synthesized artificially, which contradicts the idea of vitalism which says that organic compounds can only be made by organisms.. The reactions used in the process are different from those used in the liver, but the product is the same. About 100 million tons are produced annually for use as a nitrogen fertilizer on crops.