ProteinsProteins are the macromolecules of life. Discovered in 1838, proteins are recognized as a large number of higher organic compounds constituting living organisms and essential to their functioning. The term protein comes from the Greek word “protein” or “primary”. Proteins have many different properties and work in a variety of ways. They can function as a building material in teeth, bones and muscles, and they can serve as enzymes, hormones and neurotransmitters. Its functions are the most diverse of all families. Whether present in humans, animals, plants or single-celled bacteria, proteins are made up of units of 20 different amino acids. Proteins are made up of macromolecules called polypeptides, which are made up of monomers called amino acids. Proteins contain hundreds, thousands, and sometimes millions of these amino acids. These amino acids are made up of carbon, hydrogen, oxygen, nitrogen and sometimes sulfur. Some proteins are made up only of single polypeptides. In most cases, these are two or more polypeptides combined, sometimes with other small organic molecules or metal ions. The most basic level of protein structure, called primary structure, is the linear sequence of amino acids. However, different sequences of acids along a chain affect the structure of a protein molecule in different ways. The secondary structure of proteins often contains long chains of amino acids called strands that line up together to form sheets. These are called beta strands and the sheets are called beta pleated sheets. A protein may contain one or both alpha helices and beta pleated sheets. The alpha helices and beta pleated sheets are connected by less clear structures often grouped together as the coil. Some small proteins may be made of coils. The shape is also important. The proteins are coiled and twisted, giving it a unique shape. The shape depends on the sequence of the amino acids, which can be hydrophilic or hydrophobic. Those that are hydrophilic want contact with water and will twist to maximize contact. Those that are hydrophobic are twisted in a way to minimize contact. Changing an amino acid in the polypeptide sequence can destroy this form and prevent the protein from functioning properly, if at all. A very important function that proteins can perform is to act as catalysts. Enzymes are organic catalysts that make... middle of paper... cells, their shape, and parts of the bonds that stick cells together in tissues and organs. Thus, the sequence of amino acids in all proteins is genetically determined by the sequence of nucleotides in cellular DNA. So basically, proteins are fundamental constituents of all living organisms. They are complex molecules composed of amino acids and necessary for the chemical processes that occur in living organisms. Proteins are sometimes called macromolecular polypeptides because they are very large molecules and because the amino acids that compose them are linked by peptide bonds. The vast majority of proteins found in living organisms are made up of just 20 different types of amino acids, repeated several times and strung together in a particular order. Each type of protein has its own unique sequence of amino acids. In addition, each protein makes each living organism different.Bibliography:1. Proteins, Lexicon Universal Encyclopedia,