The primary and secondary structures are both present in a tertiary structure, the whole chain may then be folded further to give the protein molecule a complex globular shape that is known ate the tertiary structure. Similarly to the secondary structure the tertiary structure of protein is determined by a sequence of amino acids in the polypeptide chain. (Inge B et al, 2001 page 45)
This means that the tertiary structure refers to the overall three dimensional shape of a polypeptide chain. As seen in the image below. Proteins are classified into …show more content…
The Haemoglobin molecule is nearly spherical. The four polypeptide chains packed closely together, their hydrophobic R groups pointing in towards the centre of the molecule and their hydrophilic ones pointing outwards. Each chain has a tertiary structure. The interactions that occur between the hydrophobic R groups inside the molecule are very important in holding three dimensional shape. The outwards pointing hydrophilic R groups on the surface are important in maintaining the solubility. In a generic condition referred to as sickle cell anaemia, one amino acid that occurs in the surface of the chain is replaced with a different amino acid. The correct amino acid is polar, however the substitute is non polar. Having a non-polar R group on the outside of the molecule makes the haemoglobin much less soluble and this is dangerous as it causes unpleasant symptoms associated with sickle cell anaemia. This will occur in anyone whose haemoglobin is a ‘faulty type’. This is why it’s important for haemoglobin to have the particular structure is