The molecules present in the animals are called organic molecules. The portant groups of organic molecules in animals include carbohydrates, lipids, oteins, nucleotides, and nucleic acids. There are two types of molecules. Organic molecules: They contain carbon atoms.
Inorganic molecules: They lack carbon atoms A few simple molecules containing carbon are inorganic Its example is CO2
T e characteristics of organic molecules depend on properties of carbon. Carbon is an indispensable element for all life: The carbon atom has four electrons in its o ter orbital. Therefore, it must share four additional electrons by covalent bond. T is unique bonding enables carbon to bond with other carbon atoms. So it f ms chains and rings of different lengths and configurations. It also bonds with h drogen and other atoms. Carbon has only four electrons in the outer shell. So
rbon atoms can form four covalent bonds. Adjacent carbon atoms may share o e or two pairs of electrons.
S me elements share one pair of electrons and form a single covalent bond.
N w it has three free atoms to bind with three other atoms. The adjacent carbon at ms share two pairs of electrons Thus a double covalent bond is formed. It le ves each carbon free to bond to only two additional atoms.
T e organic molecules containing only carbon and hydrogen are called • rocarbons. Mostly they have their carbons bonded in a linear fashion.
Hydrocarbons form the framework of all organic molecules.
The reactive groups of the organic molecules are called functional groups. The carbon chain or ring of many organic molecules forms inactive molecular backbone. Many reactive groups or atoms are attached with this backbone The unique chemical properties and behavior of molecules are due to these functional groups. There are following functional groups: —