Protein
Protein is composed of monomers called amino acids. There are twenty different types of amino acids which are essential for human body they are known as essential amino acids. Proteins is basically a polypeptide chain of amino acids.
Role of protein
1. Enzymes:
Enzymes are proteinous in nature which catalyze different metabolic reactions.
2. Hormones:
These are also made from protein that control different physiological functions in plants and animals.
3. Antibodies:
Antibodies and some other chemical mediators are also protein in nature and have a key role in the human immune system.
Carbohydrates
Carbohydrate is a poly hydroxy aldehyde or poly hydroxy keton substance and composed of glucose monomers (simple sugar).
Role of carbohydrate:
1. As source of energy:
Carbohydrate is the main source of energy in body. During aerobic respiration each glucose molecule is broken down and produce 36 ATP.
2. Storage source
Glycogen and starch are two carbohydrates that are stored in animal and plants for energy purpose when needed.
3. structural building materials :
Cellulose is a complex carbohydrate that make cell wall composition of plant cell wall.
Nucleic acid
Nucleic acids is composed of monomers called nucleotide. Each nucleotide is consisting of three components, these are pentose sugar, nitrogenous base and phosphate group.
Role of nucleic acid
Nucleic acid play a key role in the transfer of hereditary materials from parents to offspring.