The approximate amino acid composition of gelatin is: glycine 21%, proline 12%, hydroxyproline 12%, glutamic acid 10%, alanine 9%, arginine 8%, aspartic acid 6%, lysine 4%, serine 4%, leucine 3%, valine 2%, phenylalanine 2%, threonine 2%, isoleucine 1%, hydroxylysine 1%, methionine and histidine <1% and tyrosine <0.5%.
First of all the ratio of amino acids is not correct. The specific amino acid content in protein is never higher than 10% (with a couple of exceptions). Therefore most of the glycine and proline will end up being metabolized.
In addition both glycine and proline are non-essential amino acids and gelatin lacks several essential amino acids or is very low their respective content.