 The combination of these two aspects is highly problematic. The definition from the U.S. National Library of Medicine implies that “all of the information needed to build and maintain that organism” is contained in the  DNA,[2]  which is certainly false: many environmental factors, not to mention factors in the maternal cytoplasm, are required for the first task, and even more obviously (food, light, etc.) for the second. Moreover when, as is almost always the case, an organism requires symbiotic partners for its proper functioning, such a definition will imply that the DNA of these symbionts is part of the genome of the first organism, a result that few would  welcome.[3]  The Nature definition commits the same error in its second sentence. The genome.gov definition appears to identify the chromosomes both with a set of instructions and a material entity, which appears rather problematically to conflate a material object with an abstract entity. 