STPM Biology - chapter 1: Reision essay question 31

31. Explain how the structure of collagen and haemoglobin are related to their function.



Answer:

The structure of collagen , which is a fibrous potein,consists of a primary structure of a repetitive tripeptide sequence that forms long chains and may run parallel to each other. In the secondary structure has three unbranched polypeptide chains linked to one another via cross bridges and forming a triple helix. These cross bridges involve strong coxalent bonds that help provide structural support to the collagen molecule,thereby making it resistant to stretching .Hence,collagen has an important structural role in providing physical strength to connective tissue such as tendons .While, the structure of haemoglobin ,which is a conjugated protein ,consists of sequences of amino acids forming four polypeptise chains that twist and fold into a compact shape and has haem as the prosthetic group.Two chains are a chains and the other two are b chains held together by hydrophobic interactions , hydrogen and ionic bonds. Haemoglobin has a quartenary structure, with each haem group contains a ferrous iron atom that is able to carry an oxygen molecule. Therefore, each human haemoglobin molecule is capable of carrying 4 oxygeb molecules , making it an efficient respiratory pigment involved in oxygen transport. 
Assignment submitted by C.L., Ooi, T. T., Tan, K. Y., Ho, S.S., Aiu, X. H., Wong  2011/2012 (IBM)