Answer:
Tertiary protein structure
Explanation:
The tertiary structure of the haemoglobin consists of four heme and four polypeptide subunits; two alpha chains and two beta chains, which gives it its function (ability to carry oxygen).
In the case of sickle- cell anemia which is caused by the replacement of an amino acid, glutamate with valine at position 6 of the beta chain of the haemoglobin structure, this disrupts the tertiary structure and hence its oxygen carrying ability.
