Chemists have developed ways to understand the shape and behavior of small molecules, using mathematical analysis. They might use computers to study these molecules. The DNA contained in just one cell of an organism is far too large to be read by any person, and to compare the DNA between two (or more) organisms, be they in the brother and sister, or of a completely different species, requires comparing large amounts of information to find differences. Computers are better suited to such comparisons, and computer programmers have worked with biologists to create very very large databases to store all the DNA information that has ever been learned.