How the structure of proteins are related to their functions Rachel Morris
The basic building blocks of proteins are amino acids, the biuret reaction tests for protein. A solution of sodium hydroxide is added to a sample then a few drops of copper sulphate solution, if positive – the solution will turn mauve. There are 20 different amino acids and they can be joined in any order. Therefore there can be many different functions. A protein consists of one or more polypeptide chains (a polypeptide chain being multiple amino acids joined together via condensation, producing a peptide bond). Different proteins have different shapes as the shapes are determined by the sequence of amino acids. The primary stage of a protein is a polypeptide chain, the second is where the polypeptide chain forms as an alpha helix or/and a beta pleated sheet. The tertiary structure is particularly related to its function, there are various bonds involved such as hydrogen bonds and disulphide bonds. The quaternary structure is when multiple polypeptide chains join together to perform a role.
Antibodies are specialized proteins which are secreted by B cells in a response to non-self antigens. Antibodies are made up of four polypeptide chains which are held together by disulphide bridges. There are two longer and two shorter chains which look like the letter “Y”. The ends of the antibodies have a variable region which is specific to a particular antigen. An antigen and antibody are complementary to each other and form an antigen-antibody complex. The structure of this protein is related to its function as the complexes then clump together, and then digested by white blood cells (phagocytes?).
An enzyme is a protein which catalyses reactions. Each enzyme is specific i.e. has its own shape resulting from the tertiary structure. There is an active site on an enzyme where a group of amino acids form a pocket. This active site is specific and will only bind to its complementary...
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