Proteins can easily be addressed as one of the most important molecules in animal cells. There are many varieties of protein molecules which allow a vast range of biological activities in the cell.( Williams, G.(2000))’Proteins are big compound with large molecular masses’’(Williams, G.(2000)) whose main chemical constituents are hydrogen, carbon ,oxygen and nitrogen.
A protein structure consists of a specific sequence of amino acids called the primary structure, this particular sequence determines the secondary structure of the protein which can be α-helix or β-pleated sheet. This then further folds to form the tertiary structure . The primary structure determines the eventual shape of the protein and thus its function
‘’Different proteins can appear very different and perform diverse functions’’ (S-COOL. Biology A-level: Biological Molecules and Enzymes-URL: http://www.s-cool.co.uk/alevel/biology/biological-molecules-and-enzymes/carbohydrates.html (accessed 11/11/2010)). Some of the diverse range of functions provided by proteins are transport , for example haemoglobin, which allows oxygen to be transferred throughout the body. Defence, primarily by immunoglobulin, i.e. antibodies. Structure, such as collagen and elastin that form tissue. For hormones e.g. insulin and glucagon are important for controlling blood sugar. All enzymes are proteins, enzymes control most of the reactions found in living organisms, they also transfer substrate molecules. They have a specific shape due to a specific primary structure. They are therefore specific in the reactions that they catalyse. They have an active site which is a unique shape so any one type of substrate will fit in it. (S-COOL. Biology A-level: Biological Molecules and Enzymes- [online] )