What is meant by the term "tertiary structure" of a protein? Describe the forms of bonding that could be involved.

Tertiary structures in a protein refers to the overall three-dimensional structure of the protein. The tertiary structure is primarily generated by interactions between amino-acid R groups. There are five primary forces at play which determine the tertiary structure of the protein. 1. Hydrophobic interactions: non-polar hydrophobic R-groups seek to avoid an aqueous environment and so will be found most frequently in the interior of the protein, leaving hydrophilic R-groups on the outside of the protein facing into that aqueous environment. 2. Ionic bonding between positively and negatively charged amino-acid R-groups can act to further stabilize interior structures when the are brought close together. 3. Hydrogen bonds in the polypeptide chain between R-groups can act to stabalise and shape the tertiary structure. 4. Disulphide bridges may form between two cysteine residues. These are strong covalent bonds which help to hold parts of the protein firmly together. 5. Van De Waals forces act locally to aid in holding the tertiary structure of the protein together.