Proteins are big, complex molecules that do most of the work in cells and allow your body to move. They’re built from smaller units called amino acids, which are linked together in long chains. All proteins have a central portion that’s similar but they also have side chains that give them unique characteristics. These characteristics are what determine a protein’s function. For example, positively- and negatively-charged amino acids tend to cluster together and away from water, while hydrophobic residues link up in groups and bind to other proteins. This enables a protein to fold into different shapes and interact with other proteins in specific ways.
Amino acids are coded for by combinations of three DNA building blocks, or nucleotides, and the sequence determines a protein’s 3-dimensional structure and specific function. Amino acid chains are joined together through peptide bonds to form polypeptides, which can be twisted into one of four types of proteins.Some proteins, such as hemoglobin, a protein in red blood cells that carries oxygen, are compact and soluble while others are elongated and insoluble. The structure of a protein determines its function, which is why there are two major classes of proteins: globular and fibrous proteins.Proteins provide the building blocks of every cell and tissue in your body. They’re involved in the synthesis of hormones, toxins, antibiotics and enzymes. They’re also critical for the formation and maintenance of bones and muscles. They also act as a storage site for atoms and small molecules and transport them throughout the body.