Biology - Proteins


  • Proteins, which are basically biomolecules, play wide range of functions in the body of a living organism.

  • Proteins are made up of tiny elements of different types of amino acids.

  • A sequence of amino acid residues in a protein is known particularly by the sequence of a gene; gene is encoded in the genetic code.

  • After formation, proteins exist for a fixed period of time and are then degraded and recycled.

  • The proteins get recycled by the cell's machinery by the process of protein turnover.

  • Most of the proteins contain linear polymers made up of series of up to 20 different L-α-amino acids.

  • The amino acids in a polypeptide chain are connected by peptide bonds (see the image given below).

Peptide Bond
  • The peptide bond, usually, has two resonance forms, which contribute some double-bond characters.

Protein Structure

  • Most of the proteins illustrate unique 3-dimensional structures (see image given below).

Protein Structure
  • However, proteins have not a rigid structure, but rather, proteins may vary between several related structures especially when they perform their functions.

Functions of Proteins

  • Following are the major functions of proteins −

    • In the cell, proteins are the chief actors that carry out the duties defined by the information encoded in genes.

    • Proteins are essential for the overall body growth.

    • Proteins play a role of bio-catalyst and biotic regulator.

    • Proteins provide instant energy especially during the emergency period.

    • Proteins help in catalyzing the metabolic reactions.

    • Proteins are the essential elements in DNA replication.

    • Proteins actively help in transporting molecules from one location to another in the body.

Types of Protein

  • Following are the major types of protein −

    • Enzymes − enzymes play important role especially during the breakdown of molecules. Enzymes are also required for the digestion and growth of the cell.

    • Structural Proteins − such type of proteins provide strength to cells, tissues, and organs.

    • Signaling Proteins − Such proteins facilitate cells to communicate with each other by providing signals.

    • Defensive Proteins − Such proteins help organisms to fight with infection and support damaged tissue in healing fast.

    • Hormone − Some hormones are proteins that help in metabolic activities.