This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous (Bio-Chemistry), Subject name: Biochemistry
Human growth hormone has: 
Select and explain. 
A. One polypeptide chain and one intra chaindisulphide bond, B. One polypeptide chain and two intra chaindisulphide bond, C. Two polypeptide chains joined by onedisulphide bond, D. Two polypeptide chains joined by twodisulphide bond
B: One polypeptide chain and two intra chaindisulphide bond
Answer: B: One polypeptide chain and two intra chaindisulphide bond 
Explanation: Ans. B. One polypeptide chain and two intra chaindisulphide bondGrowth hormone or somatotrophin consists of a single polypeptide with a molecular weight of about 21500. It consists of 191 amino acids. There are two disulfide bridges between the adjacent cysteine residues. GH brings about positive nitrogen balance by retaining nitrogen.