Carbohydrates, Lipids, Protein , and Nucleic acids

Carbohydrates

Almost all organism use carbohydrates as a source of energy. In addition, some carbohydrates serve as structural material. Carbohydrates are molecules composed of carbon, hydrogen, and oxygen. Glucose is the basic from of fuel in living things. It is soluble and transported by body fluids to all cells, where it is metabolized to release its energy. Glucose is the starting material for cellular respiration, and it is the main product of photosynthesis.

Lipids 

Lipids are organic molecules composed of carbon, hydrogen, and oxygen atoms. The ratio of hydrogen atoms to oxygen atoms is much higher in lipids than in carbohydrates. Lipids include steroids ( the material of which many hormones are composed), waxes and fats. Fat molecules are composed of a glycerol and one, two, or three molecules of fatty acids. A fatty acid is a long chain of carbon atoms (from 4 to 24) with a carboxyl (-COOH) group at one end.

Proteins

Proteins, among the most complex of all organic compounds, are composed of amino acids. Which contains carbon, hydrogen, oxygen, and nitrogen atoms. Certain amino acids also have sulfur atoms, phosphorous, or other trace elements such as iron or copper. Every species manufactures proteins unique to that species. Proteins also serve as a reserve source of energy for the cell. When the amino group is removed from an amino acid, the resulting compound is energy rich.

Nucleic acids

The nucleic acids are composed of smallest units called nucleotides. Nucleic acids are very large molecules. Nucleotides contain a carbohydrate molecule, a phosphate group, and a nitrogen-containing molecule that because of its properties is a nitrogenous base. Living organism have two important nucleic acids which are deoxyribonucleic acid, or DNA and the other is ribonucleic acid, or RNA.