Gelatine is a mixture of protein molecules of similar structural type. Both, Gelatine and collagen, have a sole sequence of amino acids which is determining for its functional properties.
In the case of collagen, very well disposed structures, called the tropocollagen, are joined in fibrils that together form the constituent fibers of the connective tissue.
This basic unit of collagen is formed of three polypeptidic molecules arranged in form of an helix.
Gelatine has a major capacity of binding water and its chains of helical configuration are important for the formation of gel.
Being a hydrocolloid of proteic origin it has an amphoteric character associated to the presence of amine and carboxylic groups in amino acids.