Carbon is very specific element because of its properties. It can form strong covalent bonds with a lot of different elements (hydrogen, oxygen, phosphorus, sulfur and nitrogen) thanks to its four valence electrons. This ability of carbon and specificity of compounds which forms with these elements is vital for living organisms. Carbon is also unique because of its capability to bond with other carbon atoms and form single, double or triple covalent bonds. Therefore, with their mutual connection, formation of long chains or rings of carbon is possible.

Macromolecules are giant molecules formed by joining of smaller molecules through polymerization process. There are four major categories of macromolecules: carbohydrates, lipids, nucleic acids and proteins. Carbohydrates are made of carbon, hydrogen and oxygen atoms. Their ratio is mostly 1:2:1. Their main function is to provide energy for living beings, either by storing or releasing. Also, their characteristic is to provide structural protection and support. Sugar, starch and cellulose are examples of carbohydrates. Lipids are macromolecules that are not soluble in water in general. They represent compound of carbon and hydrogen atoms almost always. Their main functions are in storing energy, forming of important parts of biological membranes and waterproof coverings. Likewise, they can be chemical messengers. Fats, oils and waxes represent lipids. Nucleic acids are nucleotides’ formed polymers. Nucleotides are monomers made upon of a 5-carbon sugar, a phosphate group (-PO4) and a nitrogenous base. Their main function is to store and transmit hereditary information. There are two sorts of nucleic acids: DNA and RNA. Their main difference is in sugar component, DNA has deoxyribose and DNA has ribose. Proteins are macromolecules consisted of nitrogen, carbon, hydrogen and oxygen. Their building element are amino acids which are composed of amino group (-NH2) and a carboxyl group (COOH) on opposite ends. These groups can form peptide bond in a way where every amino group connects with carboxyl group. They have transporting function, roll in cell processes regulation and structure formation.

Carbohydrates are hydrates of carbon usually made upon a few carbon atoms. Although they form sugars, carbohydrates are not necessarily sugars or sweet. They are essential part in DNA, RNA and ATP molecule. Simple carbohydrates are principal source of immediate energy. Lipids have polar and non polar region in their structure. They are not water soluble, and are good for storage. Provide more energy than carbohydrates. Proteins, besides carbon, hydrogen and oxygen (which are element of carbohydrates) have some other elements like nitrogen or sulfur. They have different structure and function than carbohydrates. Proteins have structural and support function in the body, as well as enzyme function as regulators of speed processes. Nucleic acids have sugar component, but their structure and function is far more different that carbohydrates themselves. Besides carbon, oxygen and hydrogen, they contain nitrogen and some of them can have aromatic hydrocarbons. Their function depends of elements in their structure. Main function of nucleic acids is in transmission of genetic information.

There are more than 20 different amino acids in our surrounding. All amino acids are for the most part the same. The only thing that differs between them is an R group that determines properties of amino acid. R group can vary from being acidic or basic, polar or non-polar or having ring structure, or containing sulfur in R group. For example, tyrosine amino acid has ring structure as R group and it gives a specific function-to produce hormone thyroxine. Tyroxine is made upon of four atoms of iodine and has an important role in proper functioning of thyroid gland. On the other hand, alanine is another amino acid which R group is methyl group (-CH3). It has important role in regulation of sugar and acid metabolism. It provides energy for brain and central nervous system and increases immunity. Therefore, you can conclude that R group plays main role in different properties of every amino acid.

Elements that differentiate the amino acids of a protein from the sugars of a carbohydrate are nitrogen and sulfur atoms in structure of some amino acids.