The tertiary structure of a protein is the further folding of the polypeptide into more complex 3D shapes; bonds that stabilise this are between the R groups
Not all proteins have this (e.g. fibrous), for those that do it is vital to function as it forms the shape of receptor/active sites (e.g. protein hormone or enzyme)
Four main bonds are involved in maintaining this structure: Hydrogen, ionic, disulphide, and hydrophobic/philic interactions
Hydrogen bonds: between electropositive (δ^+) H atoms of one R-group, and the electronegative (δ^-) O in another R-group; weakest of the bonds
Ionic bonds: Forms between R-groups with oppositely charged ions like ionised amino and carboxyl groups, stronger than hydrogen bonds but still fairly weak
Disulphide bonds: Strong covalent bonds that form between the R-groups of amino acids, such as cysteine, that contain -SH groups
Heating a protein increaseskinetic energy of molecules so the atoms vibrate more causing some weaker bonds break (e.g. hydrogen bonds, ionic bonds, and hydrophobic/phillic interactions)
Irreversibly changes the 3D shape, it’s denatured (this can also be caused by pH changes, organic solvents, high salt concentration, and the presence of heavymetal ions)
