Although most of the (1) information of a eukaryotic cell resides in nuclear DNA, some of the information necessary to make both chloroplasts and (2) is stored within these (3) themselves. This information (4) on small circular DNA molecules that are similar to the chromosomes of bacteria but very different from the long linear DNA molecules in the (5). This is strong evidence for the endosymbiotic theory of the origin of mitochondria and chloroplasts, which proposes that the small circular DNA molecules found in these organelles is all that is left of the chromosomes of the original (6) bacteria.