Discuss what you would require to know to answer the following question: of all proteins that exist on earth at this time, what fraction of them have a known structure? Take into consideration that many proteins in an organism are splice variants and that mutations of the wild type can occur in individuals. Also, do you think it is now, or would it ever be, possible to answer this question, and what would have to be done to get the answer? Can an estimation be made, and what factors would need to be estimated?