Proteins

• What do all proteins contain

  Nitrogen

  Carbon

  Hydrogen

  Oxygen
• Proteins: large complex biological molecules which play diverse roles in all organisms, which have a 3D shape for carrying out specific function
• Globular: enzymes that are biological catalysts that control biochemical reactions such as amylase
• >Transport proteins: e.g haemoglobin
• >Signal proteins: carry messages across the body (insulin)
• >Contractive protein: e.g actin and myosin (muscle contraction)
• >Defensive proteins: e.g antibiotics
• Primary- Number and sequence of amino acids in a polypeptide chain determines its structure and function. A change in amino acid can alter its shape and function.
• Secondary: The way the chain coils or folds into either a beta pleated sheet or alpha helix. Structure is maintained by H bonds between functional groups
• Tertiary: The R groups of the amino acids in the polypeptide chain determines how the chain folds into its specific 3D shape. Held by bonds between R groups. Shape is essential to function; H bonds, Ionic, Disulphide.
• Proteins are made from monomers and amino acids. Each amino acid contains a central C atom which a nitrogen containing amine group (H2N or N2H) end, a carboxyl group are attached. The remaining group called the R group, and differs in different amino acids.
• Two amino acids join to make a dipeptide in a condensation reaction. The carboxyl group from one amino acid joins with the H from the amine group in the second amino acid to form water. The water is removed in the formation of the peptide bond. Number of peptide bonds is one less than the number of amino acids joined.