protein PP

In every living organism, structure plays a large role in the function of certain things. Proteins make up nearly all living organisms, so understanding the structure of proteins can help us understand the overall structure and function of us and other living things. Proteins have four levels of structure: primary, secondary, tertiary, and quaternary. Primary structure is the sequence of amino acids, which are linked together with peptide bonds. Secondary structure are structures the sequence of amino acids often form into. Proteins usually have alpha helices and/or beta sheets. Alpha helices are helices, similar to the structure of DNA. Beta sheets are flat structures that can run parallel or antiparallel. Usually, the two middle sheets are parallel and the two sheets on the outside are antiparallel to those. The bonding that is involved in secondary structure is hydrogen bonding Tertiary structure is the overall fold of a single polypeptide chain. Quaternary structure is the folding of two or more polypeptide chains, subunits, that function together. The bonds that are involved in tertiary/quaternary structure are the noncovalent bonds.